Parenteral norovirus vaccine formulations

ABSTRACT

The present invention relates to single dose parenteral vaccine compositions comprising mixtures of monovalent Norovirus virus-like particles. Methods of conferring protective immunity against Norovirus infections in a human subject by administering such compositions are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No. 16/894,291, filed Jun. 5, 2020, which is a continuation of U.S. patent application Ser. No. 15/836,030, filed Dec. 8, 2017 (now U.S. Pat. No. 10,675,341, issued Jun. 9, 2020), which is a Divisional of U.S. patent application Ser. No. 14/796,614, filed Jul. 10, 2015 (now U.S. Pat. No. 9,867,876, issued Jan. 16, 2018), which is a Continuation of U.S. patent application Ser. No. 13/840,403, filed Mar. 15, 2013 (now U.S. Pat. No. 9,801,934, issued Oct. 31, 2017), which is a Continuation of International Patent Application No. PCT/US2012/046222, filed Jul. 11, 2012, which claims the benefit of priority of U.S. Provisional Patent Application No. 61/506,447, filed on Jul. 11, 2011, the contents of each of which are herein incorporated by reference in their entireties.

REFERENCE TO AN ELECTRONIC SEQUENCE LISTING

The contents of the electronic sequence listing (LIGO_024_05US_SeqList_ST26.xml; Size: 2,877 bytes; and Date of Creation: May 16, 2023) are herein incorporated by reference in their entirety.

FIELD OF THE INVENTION

The invention is in the field of vaccines, particularly vaccines for Noroviruses. In addition, the invention relates to methods of preparing vaccine compositions and methods of inducing and evaluating protective immune responses against Norovirus in humans.

BACKGROUND OF THE INVENTION

Noroviruses are non-cultivatable human Caliciviruses that have emerged as the single most important cause of epidemic outbreaks of nonbacterial gastroenteritis (Glass et al., 2000; Hardy et al., 1999). The clinical significance of Noroviruses was under-appreciated prior to the development of sensitive molecular diagnostic assays. The cloning of the prototype genogroup I Norwalk virus (NV) genome and the production of virus-like particles (VLPs) from a recombinant Baculovirus expression system led to the development of assays that revealed widespread Norovirus infections (Jiang et al. 1990; 1992).

Noroviruses are single-stranded, positive sense RNA viruses that contain a non-segmented RNA genome. The viral genome encodes three open reading frames, of which the latter two specify the production of the major capsid protein and a minor structural protein, respectively (Glass et al. 2000). When expressed at high levels in eukaryotic expression systems, the capsid protein of NV, and certain other Noroviruses, self-assembles into VLPs that structurally mimic native Norovirus virions. When viewed by transmission electron microscopy, the VLPs are morphologically indistinguishable from infectious virions isolated from human stool samples.

Immune responses to Noroviruses are complex, and the correlates of protection are just now being elucidated. Human volunteer studies performed with native virus demonstrated that mucosally-derived memory immune responses provided short-term protection from infection and suggested that vaccine-mediated protection is feasible (Lindesmith et al. 2003; Parrino et al. 1977; Wyatt et al., 1974).

Although Norovirus cannot be cultivated in vitro, due to the availability of VLPs and their ability to be produced in large quantities, considerable progress has been made in defining the antigenic and structural topography of the Norovirus capsid. VLPs preserve the authentic confirmation of the viral capsid protein while lacking the infectious genetic material. Consequently, VLPs mimic the functional interactions of the virus with cellular receptors, thereby eliciting an appropriate host immune response while lacking the ability to reproduce or cause infection. In conjunction with the NIH, Baylor College of Medicine studied the humoral, mucosal and cellular immune responses to NV VLPs in human volunteers in an academic, investigator-sponsored Phase I clinical trial. Orally administered VLPs were safe and immunogenic in healthy adults (Ball et al. 1999; Tacket et al. 2003). But, multiple doses of a relatively high amount of VLPs were required to observe an immune response. At other academic centers, preclinical experiments in animal models have demonstrated enhancement of immune responses to VLPs when administered intranasally with bacterial exotoxin adjuvants (Guerrero et al. 2001; Nicollier-Jamot et al. 2004; Periwal et al. 2003; Souza et al. (2007) Vaccine, Vol. 25(50):8448-59). However, protective immunity against Norovirus in humans remains elusive because the indicators of a protective immune response in humans have still not been clearly identified (Herbst-Kralovetz et al. (2010) Expert Rev. Vaccines 9(3), 299-307).

SUMMARY OF THE INVENTION

The present invention is based, in part, on the discovery that a single dose of a Norovirus vaccine elicits a rapid, robust protective immune response against Norovirus in humans when administered parenterally. Accordingly, the present invention provides a method of eliciting protective immunity against Norovirus in a human comprising administering parenterally to the human no more than a single dose of a vaccine composition, said composition comprising genogroup I and/or genogroup II Norovirus VLPs, wherein said composition induces at least a three-fold increase in Norovirus-specific serum antibody titer as compared to the titer in the human prior to administration of the composition. In certain embodiments, the increase in Norovirus-specific antibody titer is induced within seven days of administration of the single dose of the composition. In some embodiments, the vaccine composition is administered to the human via an intravenous, subcutaneous, intradermal, or intramuscular route of administration. In one embodiment, the vaccine composition is administered to the human by an intramuscular route of administration.

The single dose vaccine compositions can comprise doses of about 5 μg to about 150 of genogroup I Norovirus VLPs, genogroup II Norovirus VLPs, or both. In embodiments in which the single dose vaccine compositions comprise both genogroup I and genogroup II Norovirus VLPs, the dose of each VLP can be the same or different. In one embodiment, the composition comprises no more than 50 μg of genogroup I Norovirus VLPs. In another embodiment, the composition comprises no more than 25 μg of genogroup I Norovirus VLPs. In yet another embodiment, the composition comprises no more than 150 μg of genogroup II Norovirus VLPs. In still another embodiment, the composition comprises no more than 50 μg of genogroup II Norovirus VLPs. The Norovirus VLPs can be monovalent VLPs or multivalent VLPs.

In some aspects of the invention, genogroup I Norovirus VLPs in the vaccine compositions comprise a capsid protein derived from a genogroup I viral strain. In one embodiment, the genogroup I Norovirus VLPs comprise a capsid protein from a genogroup I, genotype 1 Norovirus. In another embodiment, the genogroup I Norovirus VLPs comprise a capsid protein from Norwalk virus. In other aspects of the invention, genogroup II Norovirus VLPs in the vaccine compositions comprise a capsid protein derived from a genogroup II viral strain. In some embodiments, the genogroup II Norovirus VLPs comprise a capsid protein from a genogroup II, genotype 4 Norovirus. In certain embodiments, the genogroup II Norovirus VLPs are VLPs generated from expression of a consensus sequence of genogroup II Norovirus. In one particular embodiment, the genogroup II Norovirus VLPs comprise a capsid protein having a sequence of SEQ ID NO: 1.

In certain embodiments, the vaccine composition further comprises at least one adjuvant. The adjuvant is preferably not a bacterial exotoxin adjuvant. In one embodiment, the adjuvant is a toll-like receptor agonist, such as monophosphoryl lipid A (MPL), flagellin, or CpG. In another embodiment, the adjuvant is aluminum hydroxide (e.g. alum). In certain embodiments, the vaccine composition comprises two adjuvants, such as MPL and aluminum hydroxide. In some embodiments, the vaccine composition may further comprise a buffer, such as L-histidine, imidazole, succinic acid, tris, and citric acid. The vaccine composition can be formulated as a dry powder or a liquid. In one embodiment, the vaccine composition is formulated as a liquid (e.g. aqueous formulation).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-FIG. 1B. Results of pan-ELISA assays measuring combined serum IgG, IgA, and IgM levels from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, 50, or 150 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The geometric mean titer for anti-GI.1 (FIG. 1A) and anti-GII.4 (FIG. 1B) antibodies is shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 2A-FIG. 2B. Results of pan-ELISA assays measuring combined serum IgG, IgA, and IgM levels from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, 50, or 150 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The geometric mean fold rise for anti-GI.1 (FIG. 2A) and anti-GII.4 (FIG. 2B) antibodies is shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 3A-FIG. 3B. Results of pan-ELISA assays measuring combined serum IgG, IgA, and IgM levels from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, 50, or 150 μs each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The percent seroresponse rates (i.e. four-fold increase in antibody titer compared to pre-immunization titers) for anti-GI.1 (FIG. 3A) and anti-GII.4 (FIG. 3B) antibodies are shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 4A-FIG. 4B. Results of ELISA assays measuring serum IgA from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, or 50 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The geometric mean titer for anti-GI.1 (FIG. 4A) and anti-GII.4 (FIG. 4B) antibodies is shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 5A-FIG. 5B. Results of ELISA assays measuring serum IgA from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, or 50 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The geometric mean fold rise for anti-GI.1 (FIG. 5A) and anti-GII.4 (FIG. 5B) antibodies is shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 6A-FIG. 6B. Results of ELISA assays measuring serum IgA from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, or 50 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The percent seroresponse rates (i.e. four-fold increase in antibody titer compared to pre-immunization titers) for anti-GI.1 (FIG. 6A) and anti-GII.4 (FIG. 6B) antibodies are shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 7A-FIG. 7B. Results of ELISA assays measuring serum IgG from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, or 50 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The geometric mean titer for anti-GI.1 (FIG. 7A) and anti-GII.4 (FIG. 7B) antibodies is shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 8A-FIG. 8B. Results of ELISA assays measuring serum IgG from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, or 50 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The geometric mean fold rise for anti-GI.1 (FIG. 8A) and anti-GII.4 (FIG. 8B) antibodies is shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 9A-FIG. 9B. Results of ELISA assays measuring serum IgG from human volunteers immunized intramuscularly with placebo (saline) or a vaccine formulation containing 5, 15, or 50 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The percent seroresponse rates (i.e. four-fold increase in antibody titer compared to pre-immunization titers) for anti-GI.1 (FIG. 9A) and anti-GII.4 (FIG. 9B) antibodies are shown for each of the dosage levels at 7 and 21 days after the first immunization and 7 and 28 days after the second immunization. Volunteers received immunizations on study days 0 and 28.

FIG. 10 . Results of pan-ELISA assays measuring combined serum IgG, IgA, and IgM levels from human volunteers immunized with either a Norovirus intranasal, monovalent vaccine as described in El Kamary et al. (2010) J Infect Dis, Vol. 202(11): 1649-1658 (LV01-103 groups) or a Norovirus intramuscular, bivalent vaccine as described in Example 1 (LV03-104 groups) at the indicated time points. Human volunteers received either placebo or two doses of either the intramuscular or intranasal vaccine formulation. The intramuscular, bivalent Norovirus vaccine contained 5 μg each of a genogroup I.1 Norovirus VLP and a genogroup 11.4 Norovirus VLP. The intranasal, monovalent vaccine contained 100 μg of a genogroup I.1 Norovirus. Volunteers receiving the intranasal vaccine or placebo were challenged with live Norovirus following the second immunization.

FIG. 11A-FIG. 11B. FACS analysis of peripheral blood mononuclear cells obtained from human volunteers on Day 0 prior to immunization with either a 5 μg dose of Norovirus intramuscular, bivalent vaccine (FIG. 11A) or placebo (FIG. 11B) and Day 7 post-immunization. CD19+ PBMC are mucosally targeted as evidenced of expression of alpha 4/beta7 homing receptor and chemokine CCR10 receptor.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to methods of eliciting a protective immunity to Norovirus infections in a subject. In particular, the present invention provides methods of eliciting a protective immunity against Norovirus in a human by parenterally administering to the human no more than a single dose of a vaccine comprising Norovirus VLPs and optionally at least one adjuvant, wherein the vaccine confers protection from or amelioration of at least one symptom of Norovirus infection. The inventors have surprisingly discovered that intramuscular administration of no more than a single dose of a vaccine composition comprising Norovirus VLPs to humans induces a rapid (i.e. within 7 days of immunization) serum seroconversion (i.e. at least a three-fold increase in antigen-specific serum antibody titers above pre-vaccination levels) that is indicative of a protective immune response against Norovirus infection and illness. The immune responses induced by this single dose vaccine composition plateau at high antibody titers similar to that observed with natural infection by administration of live virus in human challenge studies. Interestingly, a boost dose of the vaccine is not required as the immune response is not increased upon further administration of an additional vaccine dose.

The invention provides a vaccine composition comprising one or more Norovirus antigens. By “Norovirus,” “Norovirus (NOR),” “norovirus,” and grammatical equivalents herein, are meant members of the genus Norovirus of the family Caliciviridae. In some embodiments, a Norovirus can include a group of related, positive-sense single-stranded RNA, nonenveloped viruses that can be infectious to human or non-human mammalian species. In some embodiments, a Norovirus can cause acute gastroenteritis in humans. Noroviruses also can be referred to as small round structured viruses (SRSVs) having a defined surface structure or ragged edge when viewed by electron microscopy.

Included within the Noroviruses are at least five genogroups (GI, GII, GIII, GIV, and GV). GI, GII, and GIV Noroviruses are infectious in humans, while GIII Noroviruses primarily infect bovine species. GV has recently been isolated from mice (Zheng et al. (2006) Virology, Vol 346: 312-323). Representative of GIII are the Jena and Newbury strains, while the Alphatron, Fort Lauderdale, and Saint Cloud strains are representative of GIV. The GI and GII groups may be further segregated into genetic clusters or genotypes based on genetic classification (Ando et al. (2000) J. Infectious Diseases, Vol. 181 (Supp2):S336-S348; Lindell et al. (2005) J. Clin. Microbiol., Vol. 43(3): 1086-1092). As used herein, the term genetic clusters is used interchangeably with the term genotypes. Within genogroup I, there are 8 GI clusters known to date (with prototype virus strain name): GI.1 (Norwalk (NV-USA93)); GI.2 (Southhampton (SOV-GBR93)); GI.3 (Desert Shield (DSV-USA93)); GI.4 (Cruise Ship virus/Chiba (Chiba-JPN00)); GI.5 (318/Musgrove (Musgrov-GBROO)); GI.6 (Hesse (Hesse-DEU98)); GI.7 (Wnchest-GBROO); and GI.8 (Boxer-USA02). Within genogroup II, there are 19 GII clusters known to date (with prototype virus strain name): GII.1 (Hawaii (Hawaii-USA94)); GII.2 (Snow Mountain/Melksham (Msham-GBR95)); GII.3 (Toronto (Toronto-CAN93)); GII.4 (Bristol/Lordsdale (Bristol-GBR93)); GII.5 (290/Hillingdon (Hilingd-GBR00)); GII.6 (269/Seacroft (Seacrof-GBR00)); GII.7 (273/Leeds (Leeds-GBR00)); GII.8 (539/Amsterdam (Amstdam-NLD99)); GII.9 (378 (VABeach-USA01)), GIL 10 (Erfurt-DEU01); GIL 11 (SW9180JPN01); GII.12 (Wortley-GBR00); GII.13 (Faytvil-USA02); GII.14 (M7-USA03); GII.15 (J23-USA02); GII.16 (Tiffin-USA03); GII.17 (CSE1-USA03); GII.18 (QW101/2003/US) and GII.19 (QW170/2003/US).

By “Norovirus” also herein is meant recombinant Norovirus virus-like particles (rNOR VLPs). In some embodiments, recombinant expression of at least the Norovirus capsid protein encoded by ORF2 in cells, e.g., from a baculovirus vector in Sf9 cells, can result in spontaneous self-assembly of the capsid protein into VLPs. In some embodiments, recombinant expression of at least the Norovirus proteins encoded by ORF1 and ORF2 in cells, e.g., from a baculovirus vector in 519 cells, can result in spontaneous self-assembly of the capsid protein into VLPs. VLPs are structurally similar to Noroviruses but lack the viral RNA genome and therefore are not infectious. Accordingly, “Norovirus” includes virions that can be infectious or non-infectious particles, which include defective particles.

Non-limiting examples of Noroviruses include Norovirus genogroup 1 strain Hu/NoV/West Chester/2001/USA, GenBank Accession No. AY502016; Chiba virus (CHV, GenBank AB042808); Norovirus genogroup 2 strain Hu/NoV/Braddock Heights/1999/USA, GenBank Accession No. AY502015; Norovirus genogroup 2 strain Hu/NoV/Fayette/1999/USA, GenBank Accession No. AY502014; Norovirus genogroup 2 strain Hu/NoV/Fairfield/1999/USA, GenBank Accession No. AY502013; Norovirus genogroup 2 strain Hu/NoV/Sandusky/1999/USA, GenBank Accession No. AY502012; Norovirus genogroup 2 strain Hu/NoV/Canton/1999/USA, GenBank Accession No. AY502011; Norovirus genogroup 2 strain Hu/NoV/Tiffin/1999/USA, GenBank Accession No. AY502010; Norovirus genogroup 2 strain Hu/NoV/CS-E1/2002/USA, GenBank Accession No. AY50200; Norovirus genogroup 1 strain Hu/NoV/Wisconsin/2001/USA, GenBank Accession No. AY502008; Norovirus genogroup 1 strain Hu/NoV/CS-841/2001/USA, GenBank Accession No. AY502007; Norovirus genogroup 2 strain Hu/NoV/Hiram/2000/USA, GenBank Accession No. AY502006; Norovirus genogroup 2 strain Hu/NoV/Tontogany/1999/USA, GenBank Accession No. AY502005; Norwalk virus, complete genome, GenBank Accession No. NC.sub.--001959; Norovirus Hu/GI/Otofuke/1979/JP genomic RNA, complete genome, GenBank Accession No. AB187514; Norovirus Hu/Hokkaido/133/2003/JP, GenBank Accession No. AB212306; Norovirus Sydney 2212, GenBank Accession No. AY588132; Norwalk virus strain SN2000JA, GenBank Accession No. AB190457; Lordsdale virus complete genome, GenBank Accession No. X86557; Norwalk-like virus genomic RNA, Gifu′96, GenBank Accession No. AB045603; Norwalk virus strain Vietnam 026, complete genome, GenBank Accession No. AF504671; Norovirus Hu/GII.4/2004/N/L, GenBank Accession No. AY883096; Norovirus Hu/GII/Hokushin/03/JP, GenBank Accession No. AB195227; Norovirus Hu/GII/Kamo/03/JP, GenBank Accession No. AB195228; Norovirus Hu/GII/Sinsiro/97/JP, GenBank Accession No. AB195226; Norovirus Hu/GII/Ina/02/JP, GenBank Accession No. AB195225; Norovirus Hu/NLV/GII/Neustrelitz260/2000/DE, GenBank Accession No. AY772730; Norovirus Hu/NLV/Dresden174/pUS-NorII/1997/GE, GenBank Accession No. AY741811; Norovirus Hu/NLV/Oxford/B2S16/2002/UK, GenBank Accession No. AY587989; Norovirus Hu/NLV/Oxford/B4S7/2002/UK, GenBank Accession No. AY587987; Norovirus Hu/NLV/Witney/B7S2/2003/UK, GenBank Accession No. AY588030; Norovirus Hu/NLV/Banbury/B9S23/2003/UK, GenBank Accession No. AY588029; Norovirus Hu/NLV/ChippingNorton/2003/UK, GenBank Accession No. AY588028; Norovirus Hu/NLV/Didcot/B9S2/2003/UK, GenBank Accession No. AY588027; Norovirus Hu/NLV/Oxford/B8S5/2002/UK, GenBank Accession No. AY588026; Norovirus Hu/NLV/Oxford/B6S4/2003/UK, GenBank Accession No. AY588025; Norovirus Hu/NLV/Oxford/B6S5/2003/UK, GenBank Accession No. AY588024; Norovirus Hu/NLV/Oxford/B5S23/2003/UK, GenBank Accession No. AY588023; Norovirus Hu/NLV/Oxford/B6S2/2003/UK, GenBank Accession No. AY588022; Norovirus Hu/NLV/Oxford/B6S6/2003/UK, GenBank Accession No. AY588021; Norwalk-like virus isolate Bo/Thirsk10/00/UK, GenBank Accession No. AY126468; Norwalk-like virus isolate Bo/Penrith55/00/UK, GenBank Accession No. AY126476; Norwalk-like virus isolate Bo/Aberystwyth24/00/UK, GenBank Accession No. AY126475; Norwalk-like virus isolate Bo/Dumfries/94/UK, GenBank Accession No. AY126474; Norovirus NLV/IF2036/2003/Iraq, GenBank Accession No. AY675555; Norovirus NLV/IF1998/2003/Iraq, GenBank Accession No. AY675554; Norovirus NLV/BUDS/2002/USA, GenBank Accession No. AY660568; Norovirus NLV/Paris Island/2003/USA, GenBank Accession No. AY652979; Snow Mountain virus, complete genome, GenBank Accession No. AY134748; Norwalk-like virus NLV/Fort Lauderdale/560/1998/US, GenBank Accession No. AF414426; Hu/Norovirus/hiroshima/1999/JP(9912-02F), GenBank Accession No. AB044366; Norwalk-like virus strain 11MSU-MW, GenBank Accession No. AY274820; Norwalk-like virus strain B-1SVD, GenBank Accession No. AY274819; Norovirus genogroup 2 strain Hu/NoV/Farmington Hills/2002/USA, GenBank Accession No. AY502023; Norovirus genogroup 2 strain Hu/NoV/CS-G4/2002/USA, GenBank Accession No. AY502022; Norovirus genogroup 2 strain Hu/NoV/CS-G2/2002/USA, GenBank Accession No. AY502021; Norovirus genogroup 2 strain Hu/NoV/CS-G12002/USA, GenBank Accession No. AY502020; Norovirus genogroup 2 strain Hu/NoV/Anchorage/2002/USA, GenBank Accession No. AY502019; Norovirus genogroup 2 strain Hu/NoV/CS-D1/2002/CAN, GenBank Accession No. AY502018; Norovirus genogroup 2 strain Hu/NoV/Germanton/2002/USA, GenBank Accession No. AY502017; Human calicivirus NLV/GII/Langen1061/2002/DE, complete genome, GenBank Accession No. AY485642; Murine norovirus 1 polyprotein, GenBank Accession No. AY228235; Norwalk virus, GenBank Accession No. AB067536; Human calicivirus NLV/Mex7076/1999, GenBank Accession No. AF542090; Human calicivirus NLV/Oberhausen 455/01/DE, GenBank Accession No. AF539440; Human calicivirus NLV/Herzberg 385/01/DE, GenBank Accession No. AF539439; Human calicivirus NLV/Boxer/2001/US, GenBank Accession No. AF538679; Norwalk-like virus genomic RNA, complete genome, GenBank Accession No. AB081723; Norwalk-like virus genomic RNA, complete genome, isolate:Saitama U201, GenBank Accession No. AB039782; Norwalk-like virus genomic RNA, complete genome, isolate:Saitama U18, GenBank Accession No. AB039781; Norwalk-like virus genomic RNA, complete genome, isolate:Saitama U25, GenBank Accession No. AB039780; Norwalk virus strain: U25G11, GenBank Accession No. AB067543; Norwalk virus strain: U201 GII, GenBank Accession No. AB067542; Norwalk-like viruses strain 416/97003156/1996/LA, GenBank Accession No. AF080559; Norwalk-like viruses strain 408/97003012/1996/FL, GenBank Accession No. AF080558; Norwalk-like virus NLV/Burwash Landing/331/1995/US, GenBank Accession No. AF414425; Norwalk-like virus NLV/Miami Beach/326/1995/US, GenBank Accession No. AF414424; Norwalk-like virus NLV/White River/290/1994/US, GenBank Accession No. AF414423; Norwalk-like virus NLV/New Orleans/306/1994/US, GenBank Accession No. AF414422; Norwalk-like virus NLV/Port Canaveral/301/1994/US, GenBank Accession No. AF414421; Norwalk-like virus NLV/Honolulu/314/1994/US, GenBank Accession No. AF414420; Norwalk-like virus NLV/Richmond/283/1994/US, GenBank Accession No. AF414419; Norwalk-like virus NLV/Westover/302/1994/US, GenBank Accession No. AF414418; Norwalk-like virus NLV/UK3-17/12700/1992/GB, GenBank Accession No. AF414417; Norwalk-like virus NLV/Miami/81/1986/US, GenBank Accession No. AF414416; Snow Mountain strain, GenBank Accession No. U70059; Desert Shield virus DSV395, GenBank Accession No. U04469; Norwalk virus, complete genome, GenBank Accession No. AF093797; Hawaii calicivirus, GenBank Accession No. U07611; Southampton virus, GenBank Accession No. L07418; Norwalk virus (SRSV-KY-89/89/J), GenBank Accession No. L23828; Norwalk virus (SRSV-SMA/76/US), GenBank Accession No. L23831; Camberwell virus, GenBank Accession No. U46500; Human calicivirus strain Melksham, GenBank Accession No. X81879; Human calicivirus strain MX, GenBank Accession No. U22498; Minireovirus TV24, GenBank Accession No. U02030; and Norwalk-like virus NLV/Gwynedd/273/1994/US, GenBank Accession No. AF414409; sequences of all of which (as entered by the date of filing of this application) are herein incorporated by reference. Additional Norovirus sequences are disclosed in the following patent publications: WO 2005/030806, WO 2000/79280, JP2002020399, US2003129588, U.S. Pat. No. 6,572,862, WO 1994/05700, and WO 05/032457, all of which are herein incorporated by reference in their entireties. See also Green et al. (2000) J. Infect. Dis., Vol. 181 (Suppl. 2):5322-330; Wang et al. (1994) J. Virol., Vol. 68:5982-5990; Chen et al. (2004) J. Virol., Vol. 78: 6469-6479; Chakravarty et al. (2005) J. Virol., Vol. 79: 554-568; Hansman et al. (2006) J. Gen. Virol., Vol. 87:909-919; Bull et al. (2006) J. Clin. Micro., Vol. 44(2):327-333; Siebenga, et al. (2007) J. Virol., Vol. 81(18):9932-9941, and Fankhauser et al. (1998) J. Infect. Dis., Vol. 178:1571-1578; for sequence comparisons and a discussion of genetic diversity and phylogenetic analysis of Noroviruses. The nucleic acid and corresponding amino acid sequences of each are all incorporated by reference in their entirety. In some embodiments, a cryptogram can be used for identification purposes and is organized: host species from which the virus was isolated/genus abbreviation/species abbreviation/strain name/year of occurrence/country of origin. (Green et al., Human Caliciviruses, in Fields Virology Vol. 1 841-874 (Knipe and Howley, editors-in-chief, 4th ed., Lippincott Williams & Wilkins 2001)). Genogroup II, genotype 4 (GII.4) viral strains (e.g., Houston, Minerva (also known as Den Haag), and Laurens (also known as Yerseke) strains) are preferred in some embodiments. As new strains are identified and their genetic sequences are made available, one skilled in the art would be able to employ VLPs using these contemporary strains in the compositions and methods of the present invention using ordinary skill. Thus, the present invention contemplates VLPs made from such strains as suitable antigens for use in the compositions and methods described herein.

The Norovirus antigen may be in the form of peptides, proteins, or virus-like particles (VLPs). In a preferred embodiment, the Norovirus antigen comprises VLPs. As used herein, “virus-like particle(s) or VLPs” refer to a virus-like particle(s), fragment(s), aggregates, or portion(s) thereof produced from the capsid protein coding sequence of Norovirus and comprising antigenic characteristic(s) similar to those of infectious Norovirus particles. Norovirus antigens may also be in the form of capsid monomers, capsid multimers, protein or peptide fragments of VLPs, or aggregates or mixtures thereof. The Norovirus antigenic proteins or peptides may also be in a denatured form, produced using methods known in the art.

The VLPs of the present invention can be formed from either the full length Norovirus capsid protein such as VP1 and/or VP2 proteins or certain VP1 or VP2 derivatives using standard methods in the art. Alternatively, the capsid protein used to form the VLP is a truncated capsid protein. In some embodiments, for example, at least one of the VLPs comprises a truncated VP1 protein. In other embodiments, all the VLPs comprise truncated VP1 proteins. The truncation may be an N- or C-terminal truncation. Truncated capsid proteins are suitably functional capsid protein derivatives. Functional capsid protein derivatives are capable of raising an immune response (if necessary, when suitably adjuvanted) in the same way as the immune response is raised by a VLP consisting of the full length capsid protein.

VLPs may contain major VP1 proteins and/or minor VP2 proteins. In some embodiments, each VLP contains VP1 and/or VP2 protein from only one Norovirus genogroup giving rise to a monovalent VLP. As used herein, the term “monovalent” means the antigenic proteins are derived from a single Norovirus genogroup. For example, the VLPs contain VP1 and/or VP2 from a virus strain of genogroup I (e.g., VP1 and VP2 from Norwalk virus). Preferably the VLP is comprised of predominantly VP1 proteins. In one embodiment of the invention, the antigen is a mixture of monovalent VLPs wherein the composition includes VLPs comprised of VP1 and VP2 from a single Norovirus genogroup mixed with VLPs comprised of VP1 and VP2 from a different Norovirus genogroup (e.g. Norwalk virus and Houston virus) taken from multiple viral strains. Purely by way of example the composition can contain monovalent VLPs from one or more strains of Norovirus genogroup I together with monovalent VLPs from one or more strains of Norovirus genogroup II. Strains may be selected based on their predominance of circulation at a given time. In certain embodiments, the Norovirus VLP mixture is composed of GI.1 and GII.4 viral strains. More preferably, the Norovirus VLP mixture is composed of the strains of Norwalk and a consensus capsid sequence derived from genogroup II Noroviruses. Consensus capsid sequences derived from circulating Norovirus sequences and VLPs made with such sequences are described in WO 2010/017542, which is herein incorporated by reference in its entirety. For instance, in one embodiment, a consensus capsid sequence derived from genogroup II, genotype 4 (GII.4) viral strains comprises a sequence of SEQ ID NO: 1. Thus, in some embodiments, the vaccine composition comprises a mixture of monovalent VLPs, wherein one monovalent VLP comprises a capsid protein from a genogroup I Norovirus (e.g. Norwalk) and the other monovalent VLP comprises a consensus capsid protein comprising a sequence of SEQ ID NO: 1.

(SEQ ID NO: 1) M K M A S S D A N P S D G S T A N L V P E V N N E V M A L E P V V G A A I A A P V A G Q Q N V I D P W I R N N F V Q A P G G E F T V S P R N A P G E I L W S A P L G P D L N P Y L S H L A R M Y N G Y A G G F E V Q V I L A G N A F T A G K I I F A A V P P N F P T E G L S P S Q V T M F P H I I V D V R O L E P V L I P L P D V R N N F Y H Y N O S N D P T I K L I A M L Y T P L R A N N A G D D V F T V S C R V L T R P S P D F D F I F L V P P T V E S R T K P F T V P I L T V E E M T N S R F P I P L E K L F T G P S G A F V V Q P Q N G R C T T D G V L L G T T Q L S P V N I C T F R G D V T H I A G T Q E Y T M N L A S Q N W N N Y D P T E E I P A P L G T P D F V G K I Q G V L T O T T R G D G S T R G H K A T V S T G S V H F T P K L G S V Q F S T D T S N D F E T G Q N T K F T P V G V V Q D G S T T H Q N E P Q Q W V L P D Y S G R D S H N V H L A P A V A P T F P G E Q L L F F R S T M P G C S G Y P N M N L D C L L P Q E W V Q H F Y Q E A A P A Q S D V A L L R F V N P D T G R V L F E C K L H K S G Y V T V A H T G Q H D L V I P P N G Y F R E D S W V N Q F Y T L A P M G N G T G R R R A L

However, in an alternative embodiment of the invention, the VLPs may be multivalent VLPs that comprise, for example, VP1 and/or VP2 proteins from one Norovirus genogroup intermixed with VP1 and/or VP2 proteins from a second Norovirus genogroup, wherein the different VP1 and VP2 proteins are not chimeric VP1 and VP2 proteins, but associate together within the same capsid structure to form immunogenic VLPs. As used herein, the term “multivalent” means that the antigenic proteins are derived from two or more Norovirus genogroups or strains. Multivalent VLPs may contain VLP antigens taken from two or more viral strains. Purely by way of example the composition can contain multivalent VLPs comprised of capsid monomers or multimers from one or more strains of Norovirus genogroup I (e.g. Norwalk virus) together with capsid monomers or multimers from one or more strains of Norovirus genogroup II (e.g. Houston virus). Preferably, the multivalent VLPs contain capsid proteins from the strains of Norwalk and Houston Noroviruses, or other predominantly circulating strains at a given time.

The combination of monovalent or multivalent VLPs within the composition preferably would not reduce the immunogenicity of each VLP type. In particular it is preferred that there is no interference between Norovirus VLPs in the combination of the invention, such that the combined VLP composition of the invention is able to elicit immunity against infection by each Norovirus genotype represented in the vaccine. Suitably the immune response against a given VLP type in the combination is at least 50% of the immune response of that same VLP type when measured individually, preferably 100% or substantially 100%. The immune response may suitably be measured, for example, by antibody responses, as illustrated in the examples herein.

As used herein, “genogroup I Norovirus VLPs” refer to either monovalent or multivalent VLPs that comprise a capsid protein derived from one or more genogroup I Norovirus strains. In some embodiments, genogroup I Norovirus VLPs comprise a full length capsid protein from a genogroup I Norovirus (e.g. Norwalk virus). In other embodiments, genogroup I Norovirus VLPs comprise a consensus capsid protein derived from various genogroup I strains. The genogroup I strains from which the consensus capsid sequence is derived can be within the same genotype or genetic cluster or from different genotypes or genetic clusters. Similarly, as used herein, “genogroup II Norovirus VLPs” refer to either monovalent or multivalent VLPs that comprise a capsid protein derived from one or more genogroup II Norovirus strains. In some embodiments, genogroup II Norovirus VLPs comprise a full length capsid protein from a genogroup II Norovirus (e.g. Laurens or Minerva virus). In other embodiments, genogroup II Norovirus VLPs comprise a consensus capsid protein derived from various genogroup II strains. The genogroup II strains from which the consensus capsid sequence is derived can be within the same genotype or genetic cluster or from different genotypes or genetic clusters. In one embodiment, the genogroup II Norovirus VLPs comprise a capsid consensus sequence of genogroup II, genotype 4 (GII.4) Norovirus. Thus, in some embodiments, the genogroup II Norovirus VLPs comprise a capsid sequence of SEQ ID NO: 1.

Multivalent VLPs may be produced by separate expression of the individual capsid proteins followed by combination to form VLPs. Alternatively multiple capsid proteins may be expressed within the same cell, from one or more DNA constructs. For example, multiple DNA constructs may be transformed or transfected into host cells, each vector encoding a different capsid protein. Alternatively a single vector having multiple capsid genes, controlled by a shared promoter or multiple individual promoters, may be used. IRES elements may also be incorporated into the vector, where appropriate. Using such expression strategies, the co-expressed capsid proteins may be co-purified for subsequent VLP formation, or may spontaneously form multivalent VLPs which can then be purified.

A preferred process for multivalent VLP production comprises preparation of VLP capsid proteins or derivatives, such as VP1 proteins, from different Norovirus genotypes, mixing the proteins, and assembly of the proteins to produce multivalent VLPs. The VP1 proteins may be in the form of a crude extract, be partially purified or purified prior to mixing. Assembled monovalent VLPs of different genogroups may be disassembled, mixed together and reassembled into multivalent VLPs. Preferably the proteins or VLPs are at least partially purified before being combined. Optionally, further purification of the multivalent VLPs may be carried out after assembly.

Suitably the VLPs of the invention are made by disassembly and reassembly of VLPs, to provide homogenous and pure VLPs. In one embodiment multivalent VLPs may be made by disassembly of two or more VLPs, followed by combination of the disassembled VLP components at any suitable point prior to reassembly. This approach is suitable when VLPs spontaneously form from expressed VP1 protein, as occurs for example, in some yeast strains. Where the expression of the VP1 protein does not lead to spontaneous VLP formation, preparations of VP1 proteins or capsomers may be combined before assembly into VLPs.

Where multivalent VLPs are used, preferably the components of the VLPs are mixed in the proportions in which they are desired in the final mixed VLP. For example, a mixture of the same amount of a partially purified VP1 protein from Norwalk and Houston viruses (or other Norovirus strains) provides a multivalent VLP with approximately equal amounts of each protein.

Compositions comprising multivalent VLPs may be stabilized by solutions known in the art, such as those of WO 98/44944, WO 00/45841, incorporated herein by reference.

Compositions of the invention may comprise other proteins or protein fragments in addition to Norovirus VP1 and VP2 proteins or derivatives. Other proteins or peptides may also be co-administered with the composition of the invention. Optionally the composition may also be formulated or co-administered with non-Norovirus antigens. Suitably these antigens can provide protection against other diseases.

The VP1 protein or functional protein derivative is suitably able to form a VLP, and VLP formation can be assessed by standard techniques such as, for example, size exclusion chromatography, electron microscopy and dynamic laser light scattering.

The antigenic molecules of the present invention can be prepared by isolation and purification from the organisms in which they occur naturally, or they may be prepared by recombinant techniques. Preferably the Norovirus VLP antigens are prepared from insect cells such as Sf9 or H5 cells, although any suitable cells such as E. coli or yeast cells, for example, S. cerevisiae, S. pombe, Pichia pastori or other Pichia expression systems, mammalian cell expression such as CHO or HEK systems may also be used. When prepared by a recombinant method or by synthesis, one or more insertions, deletions, inversions or substitutions of the amino acids constituting the peptide may be made. Each of the aforementioned antigens is preferably used in the substantially pure state.

The procedures of production of norovirus VLPs in insect cell culture have been previously disclosed in U.S. Pat. No. 6,942,865, which is incorporated herein by reference in its entirety. Briefly, a cDNA from the 3′ end of the genome containing the viral capsid gene (ORF2) and a minor structural gene (ORF3) is cloned. The recombinant baculoviruses carrying the viral capsid genes is constructed from the cloned cDNAs. Norovirus VLPs are produced in Sf9 or H5 insect cell cultures.

In some embodiments, the vaccine composition comprises one or more adjuvants in combination with the Norovirus antigen. Most adjuvants contain a substance designed to protect the antigen from rapid catabolism, such as aluminum hydroxide or mineral oil, and a stimulator of immune responses, such as Bordatella pertussis or Mycobacterium tuberculosis derived proteins. Suitable adjuvants are commercially available as, for example, Freund's Incomplete Adjuvant and Complete Adjuvant (Pifco Laboratories, Detroit, Mich.); Merck Adjuvant 65 (Merck and Company, Inc., Rahway, N.J.); aluminum salts such as aluminum hydroxide gel (alum) or aluminum phosphate; salts of calcium, iron or zinc; an insoluble suspension of acylated tyrosine acylated sugars; cationically or anionically derivatized polysaccharides; polyphosphazenes; biodegradable microspheres; and Quil A.

Suitable adjuvants also include, but are not limited to, toll-like receptor (TLR) agonists, particularly toll-like receptor type 4 (TLR-4) agonists (e.g., monophosphoryl lipid A (MPL), synthetic lipid A, lipid A mimetics or analogs), aluminum salts, cytokines, saponins, muramyl dipeptide (MDP) derivatives, CpG oligos, lipopolysaccharide (LPS) of gram-negative bacteria, polyphosphazenes, emulsions, virosomes, cochleates, poly(lactide-co-glycolides) (PLG) microparticles, poloxamer particles, microparticles, liposomes, oil-in-water emulsions, MF59, and squalene. In some embodiments, the adjuvants are not bacterially-derived exotoxins. Preferred adjuvants include adjuvants which stimulate a Th1 type response such as 3DMPL or QS21.

Monophosphoryl Lipid A (MPL), a non-toxic derivative of lipid A from Salmonella, is a potent TLR-4 agonist that has been developed as a vaccine adjuvant (Evans et al. 2003). In preclinical murine studies intranasal MPL has been shown to enhance secretory, as well as systemic, humoral responses (Baldridge et al. 2000; Yang et al. 2002). It has also been proven to be safe and effective as a vaccine adjuvant in clinical studies of greater than 120,000 patients (Baldrick et al., 2002; Baldridge et al. 2004). MPL stimulates the induction of innate immunity through the TLR-4 receptor and is thus capable of eliciting nonspecific immune responses against a wide range of infectious pathogens, including both gram negative and gram positive bacteria, viruses, and parasites (Baldridge et al. 2004; Persing et al. 2002). Inclusion of MPL in vaccine formulations should provide rapid induction of innate responses, eliciting nonspecific immune responses from viral challenge while enhancing the specific responses generated by the antigenic components of the vaccine.

In one embodiment, the present invention provides a composition comprising monophosphoryl lipid A (MPL) or 3 De-O-acylated monophosphoryl lipid A (3D-MPL) as an enhancer of adaptive and innate immunity. Chemically 3D-MPL is a mixture of 3 De-O-acylated monophosphoryl lipid A with 4, 5 or 6 acylated chains. A preferred form of 3 De-O-acylated monophosphoryl lipid A is disclosed in European Patent 0 689 454 B1 (SmithKline Beecham Biologicals SA), which is incorporated herein by reference. In another embodiment, the present invention provides a composition comprising synthetic lipid A, lipid A mimetics or analogs, such as BioMira's PET Lipid A, or synthetic derivatives designed to function like TLR-4 agonists.

In certain embodiments, the vaccine composition comprises two adjuvants. A combination of adjuvants may be selected from those described above. In one particular embodiment, the two adjuvants are MPL and aluminum hydroxide (e.g., alum). In another particular embodiment, the two adjuvants are MPL and oil.

The term “effective adjuvant amount” or “effective amount of adjuvant” will be well understood by those skilled in the art, and includes an amount of one or more adjuvants which is capable of stimulating the immune response to an administered antigen, i.e., an amount that increases the immune response of an administered antigen composition, as measured in terms of the IgA levels in the nasal washings, serum IgG or IgM levels, or B and T-Cell proliferation. Suitably effective increases in immunoglobulin levels include by more than 5%, preferably by more than 25%, and in particular by more than 50%, as compared to the same antigen composition without any adjuvant.

In one embodiment, the present invention provides a vaccine composition formulated for parenteral administration, wherein the composition includes at least two types of Norovirus VLPs in combination with aluminum hydroxide and a buffer. The buffer can be selected from the group consisting of L-histidine, imidazole, succinic acid, tris, citric acid, bis-tris, pipes, mes, hepes, glycine amide, and tricine. In one embodiment, the buffer is L-histidine or imidazole. Preferably, the buffer is present in a concentration from about 15 mM to about 50 mM, more preferably from about 18 mM to about 40 mM, or most preferably about 20 mM to about 25 mM. In some embodiments, the pH of the antigenic or vaccine composition is from about 6.0 to about 7.0, or from about 6.2 to about 6.8, or about 6.5. The vaccine composition can be an aqueous formulation. In some embodiments, the vaccine composition is a lyophilized powder and reconstituted to an aqueous formulation.

In certain embodiments, the vaccine composition further comprises at least one adjuvant in addition to the two or more types of Norovirus VLPs, aluminum hydroxide, and a buffer. For instance, the adjuvant can be a toll-like receptor agonist, such as MPL, flagellin, CpG oligos, synthetic lipid A or lipid A mimetics or analogs. In one particular embodiment, the adjuvant is MPL.

The Norovirus VLPs included in the vaccine compositions of the invention can be any of the VLPs described herein. In one embodiment, the two types of Norovirus VLPs each comprise a capsid protein from different genogroups (e.g., genogroup I and genogroup II). For instance, one type of Norovirus VLP comprises a capsid protein derived from a genogroup I Norovirus and the other type of Norovirus VLP comprises a capsid protein derived from a genogroup II Norovirus. In one embodiment, one type of Norovirus VLP comprises a capsid protein from Norwalk virus and the other type of Norovirus VLP comprises a consensus capsid protein derived from genogroup II, genotype 4 Noroviruses (e.g., a capsid protein comprising a sequence of SEQ ID NO: 1). The vaccine composition can comprise about 5 μg to about 200 μg of each Norovirus VLP, more preferably about 15 μg to about 50 μg of each Norovirus VLP. In some embodiments, the dose of one type of Norovirus VLP is different than the dose of the other type of Norovirus VLP. For instance, in certain embodiments, the vaccine composition comprises about 5 μg to about 15 μg of a genogroup I VLP and about 15 μg to about 50 μg of a genogroup II VLP. In other embodiments, the vaccine composition comprises about 15 μg to about 50 μg of a genogroup I VLP and about 50 μg to about 150 μg of a genogroup II VLP.

In some embodiments, the vaccine compositions further comprise a pharmaceutically acceptable salt, including, but not limited to, sodium chloride, potassium chloride, sodium sulfate, amonium sulfate, and sodium citrate. In one embodiment, the pharmaceutically acceptable salt is sodium chloride. The concentration of the pharmaceutically acceptable salt can be from about 10 mM to about 200 mM, with preferred concentrations in the range of from about 100 mM to about 150 mM. Preferably, the vaccine compositions of the invention contain less than 2 mM of free phosphate. In some embodiments, the vaccine compositions comprise less than 1 mM of free phosphate. The vaccine compositions may also further comprise other pharmaceutically acceptable excipients, such as sugars (e.g., sucrose, trehalose, mannitol) and surfactants.

As discussed herein, the compositions of the invention can be formulated for administration as vaccines formulations. As used herein, the term “vaccine” refers to a formulation which contains Norovirus VLPs or other Norovirus antigens of the present invention as described above, which is in a form that is capable of being administered to a vertebrate, particularly a human, and which induces a protective immune response sufficient to induce immunity to prevent and/or ameliorate a Norovirus infection or Norovirus-induced illness and/or to reduce at least one symptom of a Norovirus infection or illness.

As used herein, the term “immune response” refers to both the humoral immune response and the cell-mediated immune response. The humoral immune response involves the stimulation of the production of antibodies by B lymphocytes that, for example, neutralize infectious agents, block infectious agents from entering cells, block replication of said infectious agents, and/or protect host cells from infection and destruction. The cell-mediated immune response refers to an immune response that is mediated by T-lymphocytes and/or other cells, such as macrophages, against an infectious agent, exhibited by a vertebrate (e.g., a human), that prevents or ameliorates infection or reduces at least one symptom thereof. In particular, “protective immunity” or “protective immune response” refers to immunity or eliciting an immune response against an infectious agent, which is exhibited by a vertebrate (e.g., a human), that prevents or ameliorates an infection or reduces at least one symptom thereof. Specifically, induction of a protective immune response from administration of the vaccine is evident by elimination or reduction of the presence of one or more symptoms of acute gastroenteritis or a reduction in the duration or severity of such symptoms. Clinical symptoms of gastroenteritis from Norovirus include nausea, diarrhea, loose stool, vomiting, fever, and general malaise. A protective immune response that reduces or eliminates disease symptoms will reduce or stop the spread of a Norovirus outbreak in a population. Vaccine preparation is generally described in Vaccine Design (“The subunit and adjuvant approach” (eds Powell M. F. & Newman M. J.) (1995) Plenum Press New York). The compositions of the present invention can be formulated, for example, for delivery to one or more of the oral, gastro-intestinal, and respiratory (e.g. nasal) mucosa. The compositions of the present invention can be formulated, for example, for delivery by injection, such as parenteral injection (e.g., intravenous, subcutaneous, intradermal, or intramuscular injection).

Where the composition is intended for delivery to the respiratory (e.g. nasal) mucosa, typically it is formulated as an aqueous solution for administration as an aerosol or nasal drops, or alternatively, as a dry powder, e.g. for rapid deposition within the nasal passage. Compositions for administration as nasal drops may contain one or more excipients of the type usually included in such compositions, for example preservatives, viscosity adjusting agents, tonicity adjusting agents, buffering agents, and the like. Viscosity agents can be microcrystalline cellulose, chitosan, starches, polysaccharides, and the like. Compositions for administration as dry powder may also contain one or more excipients usually included in such compositions, for example, mucoadhesive agents, bulking agents, and agents to deliver appropriate powder flow and size characteristics. Bulking and powder flow and size agents may include mannitol, sucrose, trehalose, and xylitol.

Where the composition is intended for parenteral injection, such as intravenous (i.v.), subcutaneous (s.c.), intradermal, or intramuscular (i.m.) injection, it is typically formulated as a liquid suspension (i.e. aqueous formulation) comprised of at least one type of Norovirus VLP and optionally at least one adjuvant. In one embodiment, the adjuvant may be MPL. In another embodiment, liquid vaccine formulated for parenteral administration may have more than one adjuvant. In a preferred embodiment, a parenterally-formulated (e.g., i.m., i.v., or s.c.-formulated) liquid vaccine comprises Norovirus genogroup I and/or genogroup II VLPs with aluminum hydroxide (e.g. alum) and monophosphoryl lipid A (MPL) as adjuvants. In one embodiment, a liquid formulation for parenteral administration comprises Norovirus genogroup antigen(s), such as one or more types of Norovirus VLPs as described herein, MPL, aluminum hydroxide, and a buffer. In another embodiment, a liquid formulation for parenteral administration comprises Norovirus genogroup antigen(s), MPL, oil, and a buffer. In certain embodiments, the buffer in the parenteral vaccine formulations is L-histidine or imidazole. Parenteral administration of liquid vaccines can be by needle and syringe, as is well known in the art.

In certain embodiments, a vaccine composition of the invention for eliciting a protective immune response against Norovirus in humans comprises genogroup I and/or genogroup II Norovirus VLPs at a dose of no more than 150 For instance, in some embodiments, the vaccine composition comprises no more than 150 μg, no more than 100 μg, no more than 50 μg, no more than 25 μg, no more than 15 μg, or no more than 10 μg of genogroup I Norovirus VLPs. In other embodiments, the vaccine composition comprises no more than 150 μg, no more than 100 μg, no more than 50 μg, no more than 25 μg, no more than 15 μg, or no more than 10 μg of genogroup II Norovirus VLPs. In certain embodiments, the vaccine composition comprises no more than 150 μg of each genogroup I and genogroup II Norovirus VLPs. In such embodiments, the dose of genogroup I Norovirus VLPs and genogroup II VLPs can be the same or different. For instance, in one embodiment, the vaccine composition may comprise no more than 50 μg of genogroup I Norovirus VLPs and no more than 150 μg of genogroup II Norovirus VLPs. In another embodiment, the vaccine composition may comprise no more than 25 μg of genogroup I Norovirus VLPs and no more than 50 μg of genogroup II Norovirus VLPs. In other embodiments, the vaccine composition may comprise no more than 15 μg of genogroup I Norovirus VLPs and no more than 50 μg of genogroup II Norovirus VLPs. In still other embodiments, the vaccine composition may comprise no more than 25 μg of genogroup I Norovirus VLPs and no more than 150 μg of genogroup II Norovirus VLPs.

The genogroup I and genogroup II Norovirus VLPs can be derived from any of the Norovirus strains described herein. In one embodiment, the genogroup I Norovirus VLPs are genogroup I, genotype 1 (GI.1) VLPs (i.e. comprise a capsid protein from a GI.1 Norovirus). In another embodiment, the genogroup I Norovirus VLPs are Norwalk VLPs. In another embodiment, the genogroup II Norovirus VLPs are genogroup II, genotype 4 (GII.4) VLPs. In still another embodiment, the genogroup II Norovirus VLPs are VLPs generated from expression of a consensus sequence of genogroup II Norovirus. In a particular embodiment, the genogroup II Norovirus VLPs comprise a capsid protein having a sequence of SEQ ID NO: 1.

The vaccine compositions hereinbefore described may be lyophilized and stored anhydrous until they are ready to be used, at which point they are reconstituted with diluent. Alternatively, different components of the composition may be stored separately in a kit (any or all components being lyophilized). The components may remain in lyophilized form for dry formulation or be reconstituted for liquid formulations, and either mixed prior to use or administered separately to the patient. In some embodiments, the vaccine compositions are stored in kits in liquid formulations and may be accompanied by delivery devices, such as syringes equipped with needles. In other embodiments, the liquid vaccine compositions may be stored within the delivery devices in a kit. For example, a kit may comprise pre-filled syringes, autoinjectors, or injection pen devices containing a liquid formulation of a vaccine composition described herein.

The lyophilization of vaccines is well known in the art. Typically the liquid antigen is freeze dried in the presence of agents to protect the antigen during the lyophilization process and to yield a cake with desirable powder characteristics. Sugars such as sucrose, mannitol, trehalose, or lactose (present at an initial concentration of 10-200 mg/mL) are commonly used for cryoprotection of protein antigens and to yield lyophilized cake with desirable powder characteristics. Lyophilizing the compositions theoretically results in a more stable composition.

The amount of antigen in each vaccine composition is selected as an amount which induces a robust immune response without significant, adverse side effects. Such amount will vary depending upon which specific antigen(s) is employed, route of administration, and adjuvants used. In general, the dose administered to a patient, in the context of the present invention should be sufficient to effect a protective immune response in the patient over time, or to induce the production of antigen-specific antibodies. Thus, the composition is administered to a patient in an amount sufficient to elicit an immune response to the specific antigens and/or to prevent, alleviate, reduce, or cure symptoms and/or complications from the disease or infection, and thus reduce or stop the spread of a Norovirus outbreak in a population. An amount adequate to accomplish this is defined as a “therapeutically effective dose.”

The vaccine compositions of the present invention may be administered via a non-mucosal or mucosal route. These administrations may include in vivo administration via parenteral injection (e.g. intravenous, subcutaneous, intradermal, and intramuscular) or other traditional direct routes, such as buccal/sublingual, rectal, oral, nasal, topical (such as transdermal and ophthalmic), vaginal, pulmonary, intraarterial, intraperitoneal, intraocular, or intranasal routes or directly into a specific tissue. Other suitable routes of administration include transcutaneous, subdermal, and via suppository. In one embodiment, the vaccine is administered by a parenteral route of administration, such as intravenous, subcutaneous, intradermal, or intramuscular. In certain embodiments, the vaccine is administered by an intramuscular route of administration. Administration may be accomplished simply by direct administration using a needle, catheter or related device (e.g. pre-filled syringes or autoinjectors), at a single time point or at multiple time points. Other parenteral formulations may be delivered subcutaneously or intradermally by microinjection or skin patch delivery methods.

The present invention provides methods for eliciting protective immunity against Norovirus in a subject comprising parenterally administering to the subject no more than a single dose of a vaccine composition of the invention, wherein said vaccine comprises genogroup I and/or genogroup II Norovirus VLPs as described herein and optionally at least one adjuvant. In such embodiments, the single dose vaccine composition induces at least a three-fold increase in Norovirus-specific serum antibody titer as compared to the titer in the human prior to administration of the composition. In some embodiments, the single dose vaccine composition induces at least a six-fold increase in Norovirus-specific serum antibody titer as compared to the titer in the human prior to administration of the composition. In other embodiments, the single dose vaccine composition induces a Norovirus-specific serum antibody titer comparable to the antibody titer induced by exposure to live Norovirus in a natural infection—i.e., a greater than ten-fold increase in Norovirus-specific serum antibody as compared to the titer in the human prior to administration of the composition. In certain embodiments, the single dose vaccine composition induces the increase in Norovirus-specific serum antibody titer within seven days of administration of the composition. Preferably, the single dose vaccine composition is administered by an intravenous, subcutaneous, or intramuscular route of administration. In a certain embodiment, the single dose vaccine composition is administered intramuscularly to the human.

As described herein, in some embodiments, the single dose vaccine compositions suitable for use in the method comprise no more than 150 μg each of genogroup I and/or genogroup II Noroviruses. For instance, in some embodiments, the vaccine composition comprises no more than 150 μg, no more than 100 μg, no more than 50 μg, no more than 25 μg, no more than 15 μg, or no more than 10 μg of genogroup I Norovirus VLPs. In other embodiments, the vaccine composition comprises no more than 150 μg, no more than 100 μg, no more than 50 μg, no more than 25 μg, no more than 15 μg, or no more than 10 μg of genogroup II Norovirus VLPs. In certain embodiments, the vaccine composition comprises no more than 50 μg of each genogroup I and genogroup II Norovirus VLPs. In embodiments in which the single dose vaccine composition comprises both genogroup I and genogroup II Norovirus VLPs, the dose of genogroup I Norovirus VLPs and genogroup II VLPs can be the same or different. For instance, in one embodiment, the vaccine composition may comprise no more than 50 μg of genogroup I Norovirus VLPs and no more than 150 μg of genogroup II Norovirus VLPs. In another embodiment, the vaccine composition may comprise no more than 25 μg of genogroup I Norovirus VLPs and no more than 50 μg of genogroup II Norovirus VLPs. In other embodiments, the vaccine composition may comprise no more than 15 μg of genogroup I Norovirus VLPs and no more than 50 μg of genogroup II Norovirus VLPs. In still other embodiments, the vaccine composition may comprise no more than 25 μg of genogroup I Norovirus VLPs and no more than 150 μg of genogroup II Norovirus VLPs.

In one embodiment of the method, the subject is a human and the vaccine confers protection from one or more symptoms of Norovirus infection. Although others have reported methods of inducing an immune response with Norovirus antigens (see U.S. Patent Application Publication No. US 2007/0207526), the indicators of a protective immune response against Norovirus in humans have still not been clearly identified (Herbst-Kralovetz et al. (2010) Expert Rev. Vaccines 9(3), 299-307). Unlike several vaccines currently licensed in the U.S. where effectiveness of the vaccine correlates with serum antibodies, studies have shown that markers of an immune response, such as increased titers of serum IgG antibodies against Norwalk virus, are not associated with protective immunity in humans (Johnson et al. (1990) J. Infectious Diseases 161: 18-21). Moreover, another study examining Norwalk viral challenge in humans indicated that susceptibility to Norwalk infection was multifactorial and included factors such as secretor status and memory mucosal immune response (Lindesmith et al. (2003) Nature Medicine 9: 548-553).

Because Norovirus is not able to be cultured in vitro, no viral neutralization assays are currently available. A functional assay which serves as a substitute for the neutralization assay is the hemagglutination inhibition (HAI) assay (see Example 1). HAI measures the ability of Norovirus vaccine-induced antibodies to inhibit the agglutination of antigen-coated red blood cells by Norovirus VLPs because Norovirus VLPs bind to red blood cell antigens (e.g. histo-blood group antigens). This assay is also known as a carbohydrate blocking assay, as it is indicative of the functional ability of antibodies to block binding of the virus or VLPs to blood group antigen carbohydrates on a red blood cell. In this assay, a fixed amount of Norovirus VLPs is mixed with a fixed amount of red blood cells and serum from immunized subjects. If the serum sample contains functional antibodies, the antibodies will bind to the VLPs, thereby inhibiting the agglutination of the red blood cells. As used herein, “functional antibodies” refer to antibodies that are capable of inhibiting the interaction between Norovirus particles and red blood cell antigens. In other words, functional antibody titer is equivalent to histo-blood group antigen (HBGA) or carbohydrate blocking antibody titer. The serum titer of Norovirus-specific functional antibodies can be measured by the HAI assay described above. The serum titer of Norovirus-specific functional antibodies can also be measured using an ELISA-based assay in which a carbohydrate H antigen is bound to microtiter wells and Norovirus VLP binding to H antigen is detected in the presence of serum (see Example 1 and Reeck et al. (2010) J Infect Dis, Vol. 202(8):1212-1218). An increase in the level of Norovirus-specific functional antibodies can be an indicator of a protective immune response. Thus, in one embodiment, the administration of the vaccine elicits a protective immunity comprising an increase in the serum titer of Norovirus-specific functional antibodies as compared to the serum titer in a human not receiving the vaccine. The serum titer of Norovirus-specific functional antibodies indicative of a protective immune response is preferably a geometric mean titer greater than 40, 50, 75, 100, 125, 150, 175, 200 as measured by the HAI assay or blocking titer (BT)₅₀ (50% inhibition of H antigen binding by Norovirus VLPs) geometric mean titer of greater than 100, 150, 200, 250, 300, 350, 400, 450, or 500 as measured by the H antigen binding assay. In one embodiment, the serum titer of Norovirus-specific functional antibodies is a geometric mean titer greater than 40 as measured by the HAI assay. In another embodiment, the serum titer of Norovirus-specific functional antibodies is a geometric mean titer greater than 100 as measured by the HAI assay. In another embodiment, the serum titer of Norovirus-specific functional antibodies is a BT₅₀ geometric mean titer greater than 100 as measured by the H antigen binding assay. In still another embodiment, the serum titer of Norovirus-specific functional antibodies is a BT₅₀ geometric mean titer greater than 200 as measured by the H antigen binding assay.

In a further aspect, the administration of the vaccine elicits a protective immunity comprising an IgA mucosal immune response and an IgG systemic immune response by administering parenterally (preferably intramuscularly) to the subject no more than a single dose of an antigenic or vaccine composition comprising one or more types of Norovirus antigens and optionally at least one effective adjuvant. The inventors have surprisingly found that parenteral administration of the Norovirus vaccine compositions described herein induces a robust IgA response in addition to a strong IgG response. Typically, strong IgA responses are only observed when vaccines are administered through a mucosal route of administration.

In certain embodiments, the administration of the vaccine elicits a protective immunity comprising an increase in the level of IgA Norovirus-specific antibody secreting cells in the blood as compared to the level in a human not receiving the vaccine. In some embodiments, the administration of the vaccine elicits a protective immunity comprising an increase in the level of IgA Norovirus-specific antibody secreting cells in the blood as compared to the level in the human before receiving the vaccine. In one embodiment, the IgA Norovirus-specific antibody secreting cells are CCR10+, CD19+, CD27+, CD62L+, and α4β7+. Antibody secreting cells with this marker profile are capable of homing to both peripheral lymphoid tissue, such as Peyer's patch in the gut, and mucosal lymphoid tissue, such as the gut mucosa. In one embodiment, the number of CCR10+, CD19+, CD27+, CD62L+, and α4β7+ IgA antibody secreting cells is greater than about 500, about 700, about 1,000, about 1,500, or greater than about 2,000 cells per 1×10⁶ peripheral blood monocytes. In another embodiment, the IgA Norovirus-specific antibody secreting cells are CCR10+, CD19+, CD27+, CD62L−, and α4β7+. Antibody secreting cells with this marker profile generally exhibit homing only to mucosal sites and can be indicative of a memory B-cell response. In some embodiments in which the vaccine is administered intramuscularly, the number of CCR10+, CD19+, CD27+, CD62L−, and α4β7+ IgA antibody secreting cells is greater than about 5,000, about 6,500, about 7,000, about 10,000, about 13,000, about 15,000, or greater than about 20,000 cells per 1×10⁶ peripheral blood monocytes.

Similar findings have been observed with vaccines for other viruses, such as rotavirus. For rotavirus vaccines, there is controversy over whether serum antibodies are directly involved in protection or merely reflect recent infection (Jiang, 2002; Franco, 2006). Defining such correlates of protection is particularly difficult in the context of diarrheal diseases such as rotavirus or norovirus, where preclinical studies inferring protection may be multifaceted with contributions from mucosal immunity (such as intestinal IgA), cytokine elaboration, and cell mediated immunity. The difficulty in measuring such immune responses during clinical development, and the lack of correlation to serum antibody measurements, requires that the effectiveness of a vaccine for these types of viruses can only be demonstrated through human clinical challenge experiments.

As mentioned above, administration of a vaccine composition of the present invention prevents and/or reduces at least one symptom of Norovirus infection. Symptoms of Norovirus infection are well known in the art and include nausea, vomiting, diarrhea, and stomach cramping. Additionally, a patient with a Norovirus infection may have a low-grade fever, headache, chills, muscle aches, and fatigue. The invention also encompasses a method of inducing a protective immune response in a subject experiencing a Norovirus infection by administering to the subject a vaccine formulation of the invention such that at least one symptom associated with the Norovirus infection is alleviated and/or reduced. A reduction in a symptom may be determined subjectively or objectively, e.g., self assessment by a subject, by a clinician's assessment or by conducting an appropriate assay or measurement (e.g. body temperature), including, e.g., a quality of life assessment, a slowed progression of a Norovirus infection or additional symptoms, a reduced severity of Norovirus symptoms or suitable assays (e.g. antibody titer, RT-PCR antigen detection, and/or B-cell or T-cell activation assay). An effective response may also be determined by directly measuring (e.g., RT-PCR) virus load in stool samples, which reflects the amount of virus shed from the intestines). The objective assessment comprises both animal and human assessments.

The invention also provides a method of generating antibodies to one or more Norovirus antigens, said method comprising administration of a vaccine composition of the invention as described above to a subject. These antibodies can be isolated and purified by routine methods in the art. The isolated antibodies specific for Norovirus antigens can be used in the development of diagnostic immunological assays. These assays could be employed to detect a Norovirus in clinical samples and identify the particular virus causing the infection (e.g. Norwalk, Houston, Snow Mountain, etc.). Alternatively, the isolated antibodies can be administered to subjects susceptible to Norovirus infection to confer passive or short-term immunity.

The invention will now be illustrated in greater detail by reference to the specific embodiments described in the following examples. The examples are intended to be purely illustrative of the invention and are not intended to limit its scope in any way.

EXAMPLES Example 1. Dose Escalation, Safety and Immunogenicity Study of Intramuscular Norovirus Bivalent Virus-Like-Particle (VLP) Vaccine in Humans (LV03-104 Study), Cohort A

This example describes Cohort A of a randomized, multi-site, dose-escalation study of the safety and immunogenicity of four dosage levels of an intramuscular (IM) Norovirus Bivalent VLP Vaccine adjuvanted with monophosphoryl lipid A (MPL) and aluminum hydroxide (AlOH) compared to placebo in adult subjects. Approximately 48 subjects 18 to 49 years of age were enrolled in the cohort. Subjects received two doses of the vaccine or placebo, by intramuscular (IM) injection, 28 days apart using a 1.5 inch (38 mm) needle.

The Norovirus Bivalent VLP Vaccine contained genogroup I, genotype 1 (GI.1) and genogroup II, genotype IV (GII.4) VLPs as the antigens, and Monophosphoryl Lipid A (MPL) and aluminum hydroxide (AlOH) as adjuvants, sodium chloride (NaCl) and L-histidine (L-His) as buffer (pH 6.3-6.7), ethanol and water for injection. The composition of the intramuscular Norovirus Bivalent VLP Vaccine is summarized in Table 1. The GII.4 VLPs comprised a capsid sequence of SEQ ID NO: 1, which was derived from three GII.4 strains.

TABLE 1 Final Drug Product Composition for Four IM Norovirus Bivalent VLP Vaccine Formulations per 0.5 mL GI.1- GII.4 VLP VLP MPL Al* NaCl L-His Ethanol Formulation (μg) (μg) (μg) (mg) (mg) (mg) (mg)  10 μg Dosage 5 5 50 0.5 4.38 1.55 19.7  30 μg Dosage 15 15 50 0.5 4.38 1.55 19.7 100 μg Dosage 50 50 50 0.5 4.38 1.55 19.7 300 μg Dosage 150 150 50 0.5 4.38 1.55 19.7 *as Aluminum Hydroxide

Placebo was sterile normal saline for injection (0.9% NaCl and preservative-free). The dose escalation of the vaccine was conducted as follows: after appropriate screening for good health, subjects in Cohort A were enrolled sequentially into each of four dosage groups of −12 subjects each (Dosage Groups A1, A2, A3, and A4). Dosage Groups A1, A2, A3, and A4 represent bivalent antigenic dosages of 5/5 μg, 15/15 μg, 50/50 μg, and 150/150 μg, respectively, of the G I.1 and GII.4 norovirus. Subjects in each dosage group were randomized 5:1 to receive vaccine or placebo. Subjects in Dosage Group A1 received their respective randomized treatment (10 subjects received 5/5 μg vaccine and 2 subjects received placebo). Subjects were followed for safety assessment by review of the symptoms recorded on the memory aid (Days 0-7) and interim medical histories from the Day 7, 21, 28, 35, and 56 visits. Safety data was reviewed by the Central Safety Monitor (CSM). After the 7-day post Dose 2 safety data (Study Day 35) were available for review from subjects in Dosage Group A1 and considered acceptable, subjects in Dosage Group A2 were eligible to receive their initial dose. The same rule applied for dosing in the subsequent dosage groups; that is, after the 7-day post Dose 2 safety data (Study Day 35) were available for review from a dosage group, the next dosage group was eligible to receive their initial dose.

At the end of enrollment in Cohort A, approximately 10 subjects in each Dosage Group received vaccine (total of 40 vaccines) and 2 subjects in each group received saline (total of approximately 8 saline control recipients).

The subjects kept a daily memory aid of solicited symptoms including four local injection site reactions, such as pain, tenderness, redness, and swelling, and 10 systemic signs or symptoms including daily oral temperature, headache, fatigue, muscle aches, chills, joint aches and gastrointestinal symptoms of nausea, vomiting, diarrhea, abdominal cramps/pain for Days 0 through 7 after each dose of IM Norovirus Bivalent VLP Vaccine or control. The redness and swelling at the injection site was measured and recorded daily for 7 days after each injection.

Interim medical histories were obtained at each follow-up visit on Days 7+3, 21+3, 28+3, 35+3, 56+7, 180+14, and 393+14 and at the follow-up telephone call on Day 265+14; subjects were queried about interim illness, doctor's visits, any serious adverse events (SAEs), and onset of any significant new medical conditions. Subjects had a CBC with WBC differential and platelet count, and serum BUN, creatinine, glucose, AST, and ALT assessed at screening and on Days 21 and 35 (˜7 days after each dose) to assess continuing eligibility and safety, respectively.

Blood from subjects was collected before vaccination on Day 0 and on Days 7+3, 21+3, 28+3, 35+3, 56+7, 180+14, and 393+14 to measure serum antibodies (IgG, IgA, and IgM separately and combined) to IM Norovirus Bivalent VLP Vaccine by enzyme-linked immunosorbent assays (ELISA). Serum carbohydrate blocking activity and serum HAI antibodies were also measured. For subjects in Cohort A, antibody secreting cells (ASCs), homing markers, memory B cells and cellular immune responses were assayed.

The following methods were used to analyze the blood samples collected from immunized individuals or individuals receiving the placebo.

Serum Antibody Measurements by ELISA

Measurement of antibodies to norovirus by ELISA was performed for all subjects, using purified recombinant Norovirus VLPs (GI.1 and GII.4 separately) as target antigens to screen the coded specimens. Briefly, norovirus VLPs in carbonate coating buffer pH 9.6 were used to coat microtiter plates. Coated plates were washed, blocked, and incubated with serial two-fold dilutions of test serum followed by washing and incubation with enzyme-conjugated secondary antibody reagents specific for human total IgG, IgG1, IgG2, IgG3, IgG4, IgA and IgM. Appropriate substrate solutions were added, color developed, plates read and the IgG, IgA and IgM endpoint titers determined in comparison to a reference standard curve for each antibody class. Geometric mean titers (GMTs), geometric mean fold rises (GMFRs) and seroresponse rates for each group was determined. Seroresponse was defined as a 4-fold increase in antibody titer compared to pre-immunization titers.

Norovirus Carbohydrate Histo-Blood-Group Antigens (HBGA) Blocking Activity

Blocking assays to measure the ability of serum antibodies to inhibit NV VLP binding to H type 1 or H type 3 synthetic carbohydrates were performed as previously described (Reeck et al. (2010) J Infect Dis, Vol. 202(8):1212-1218). Briefly, NV VLPs for the blocking assays were incubated with an equal volume of serum, and serially two-fold diluted from a starting dilution of 1:25. Neutravidin-coated, 96-well microtiter plates were washed and coated with 2.5 μg/mL of either synthetic polyvalent H type 1-PAA-biotin or polyvalent H type 3-PAA-biotin. The sera-VLP solutions were added. Plates were washed and rabbit polyclonal sera specific to NV VLPs was added, washed, and followed by incubation with horseradish peroxidase conjugated goat anti-rabbit IgG. The color was developed with tetramethylbenzidine peroxidase liquid substrate and stopped with 1M phosphoric acid. Optical density was measured at 450. Positive and negative controls were performed. Fifty-percent blocking titers (BT50) were determined, defined as the titer at which OD readings (after subtraction of the blank) are 50% of the positive control. A value of 12.5 was assigned to samples with a BT50 less than 25. Geometric mean titers (GMTs), geometric mean fold rises (GMFRs) and seroresponse rates for each group were determined. Seroresponse was defined as a 4-fold increase in antibody titer compared to pre-immunization titers. A blocking control serum sample was used as an internal control. An assay to confirm the specificity of the blocking was performed using the same protocol for the blocking assay with the following exceptions: after coating with carbohydrate, sera was incubated directly on the plate without first pre-incubating with VLP. After washing, VLPs were incubated on the plate and detected as for the blocking assay.

Norovirus Hemagglutination Antibody Inhibition (HAI) Assay

Vaccine-induced antibodies were examined for the capacity to inhibit hemagglutination of 0-type human RBCs by the norovirus VLPs as previously described (El Kamary et al. (2010) J Infect Dis, Vol. 202(11): 1649-58). HAI titers were calculated as the inverse of the highest dilution that inhibited hemagglutination with a compact negative RBC pattern and are presented as GMTs, GMFRs and >4-fold rises.

Norovirus GI.1 and GII.4 VLPs were separately serially diluted and incubated with an equal volume of a 0.5% human RBC suspension in a 96-well V bottom plate. The amount of norovirus VLP antigens corresponding to 4 HA units were determined and confirmed by back titration. Test sera were heat inactivated at 56 C for 30 minutes and treated with freshly prepared 25% Kaolin suspension. To eliminate serum inhibitors, test samples were pre-adsorbed with RBCs. The HAI assay were performed as follows: pre-treated sera (diluted 2-fold in PBS pH 5.5) were added to 96 well V-plates and incubated with an equal volume of Norovirus GI.1 and GII.4 VLP antigen, respectively, containing 4 HA units. A suspension of 0.5% RBCs was added to each well and plates incubated for an additional 90 minutes at 4 C. Wells containing only PBS or antigen without serum served as negative and positive controls, respectively. Geometric mean titers (GMTs), geometric mean fold rises (GMFRs) and seroresponse rates for each group were determined. Seroresponse was defined as a 4-fold increase in antibody titer compared to pre-immunization titers.

Antibody Secreting Cell Assays

PBMCs were isolated from approximately 60 mL of anti-coagulated blood on Days 0, 7+3, 28+3, and 35+3 after administration of IM Norovirus Bivalent VLP Vaccine or placebo. Approximately 25 mL of blood for fresh PBMC assays and 35 mL of blood for cryopreservation of PBMCs was obtained. ASC assays detect cells secreting antibodies to norovirus VLPs (Tacket et al. (2000) J. Infect. Dis., Vol. 182:302-305; Tacket et al. (2003) Clin. Immunol., Vol. 108:241-247; El Kamary et al. (2010) J Infect Dis, Vol. 202(11): 1649-58). Fresh PBMCs were evaluated for ASC frequency and determination of homing markers from a subset of subjects. Cryopreserved PBMCs from subjects participating in Cohort A were evaluated for ASC frequency. The response rate and mean number of ASC per 10⁶ PBMCs at each time point for each group are described. A positive response is defined as a post-vaccination ASC count per 10⁶ PBMCs that is at least 3 standard deviations (SD) above the mean pre-vaccination count for all subjects (in the log metric) and at least 8 ASC spots, which corresponds to the mean of medium-stimulated negative control wells (2 spots) plus 3 SD as determined in similar assays.

Measurement of Norovirus Virus-Specific Memory B-Cells

Anti-coagulated blood was collected only in Cohort A subjects (approximately 25 mL on Days 0, 28, 56 and 180) to measure memory B cells on days 0, 28, 56 and 180 after vaccination using an ELISpot assay preceded by in vitro antigen stimulation (Crotty et al. (2004) J. Immunol. Methods, Vol. 286:111-122.; Li et al. (2006) J. Immunol. Methods, Vol. 313:110-118). Peripheral blood mononuclear cells (5×10⁶ cells/mL, 1 mL/well in 24-well plates) were incubated for 4 days with norovirus GI.1 and GII.4 VLP antigens separately to allow for clonal expansion of antigen-specific memory B cells and differentiation into antibody secreting cells. Controls included cells incubated in the same conditions in the absence of antigen and/or cells incubated with an unrelated antigen. Following stimulation, cells were washed, counted, and transferred to ELISpot plates coated with Norwalk VLP. To determine frequency of virus-specific memory B cells per total Ig-secreting B lymphocytes, expanded B cells were also added to wells coated with anti-human IgG and anti-human IgA antibodies. Bound antibodies were revealed with HRP-labeled anti-human IgG or anti-human IgA followed by appropriate substrate. Conjugates to IgA and IgG subclasses (IgA1, IgA2 and IgG1-4) are also used to determine antigen-specific subclass responses that may be related with distinct effector mechanisms and locations of immune priming. Spots were counted with an ELISpot reader. The expanded cell populations for each subject were examined by flow cytometry to confirm their memory B cell phenotype, i.e. CD19+, CD27+, IgG+, IgM+, CD38+, IgD, among others (Crotty et al. (2004) J. Immunol. Methods, Vol. 286:111-122.; Li et al. (2006) J. Immunol. Methods, Vol. 313:110-118).

Cellular Immune Responses

Anti-coagulated blood (approximately 25 mL on Days 0, 28, 56, and 180) from subjects in Cohort A were collected as coded specimens and the PBMCs isolated and cryopreserved in liquid nitrogen for possible future evaluation of CMI responses to norovirus GI.1 and GII.4 VLP antigens. Assays that are performed include PBMC proliferative and cytokine responses to norovirus GI.1 and GII.4 VLP antigens by measuring interferon (IFN)-γ and interleukin (IL)-4 levels among others according to established techniques (Samandari et al. (2000) J. Immunol., Vol. 164:2221-2232; Tacket et al. (2003) Clin. Immunol., Vol. 108:241-247). T cell responses are also evaluated.

Results

Safety assessment included local and systemic solicited symptoms for 7 days and unsolicited symptoms for 28 days after each dose. Serious Adverse Events are monitored for 12 months. Immunogenicity was assessed with serum obtained prior to and after each vaccination for Pan-ELISA antibodies (IgG, IgA and IgM combined) and peripheral blood mononuclear cells (PBMCs) for IgG and IgA antibody secreting cells (ASC) via Elispot.

All four dosage groups have been enrolled for Cohort A with post dose two safety data available from all four dosage groups (40 vaccines total). Among the 40 vaccines, pain or tenderness were the most common local symptoms reported after either dose, whereas swelling or redness was infrequent. No severe local symptoms were reported. Systemic symptoms of headache, myalgia, or malaise after either dose were reported by less than half of the vaccines. No vaccines reported fever. No related SAEs were reported.

As shown in FIGS. 1A-3B, robust anamnestic Pan-ELISA antibody responses (combined IgG, IgA, and IgM) were observed to both VLP antigens 7 days after the first dose of the lowest dosage (5 μg GI.1+5 μg of GII.4 VLPs). The second dose did not boost the post dose one responses. Similar results were observed for antigen-specific serum IgG and serum IgA responses measured separately (FIGS. 4A-9B). Dose-dependent responses were observed for the antibody responses to both antigens (FIGS. 1A-9B). However, the maximal response to the GI.1 VLP appeared to be achieved with a lower dose than the maximal response to the GII.4 VLP (15 μg vs. 50 μg). Interestingly, the single dose of the intramuscularly administered Norovirus bivalent vaccine induced a surprisingly, significantly greater antigen-specific antibody titer than the titer induced by two doses of an intranasally administered monovalent VLP vaccine comprising a 20 fold higher VLP dose (FIG. 10 ; compare LV03-104 5 μg group to LV01-103 100 μg group). Moreover, the low dose (5 μg), IM bivalent Norovirus vaccine produced a Norovirus-specific antibody titer similar to that induced in humans exposed to the native Norovirus (FIG. 10 ).

Robust IgG and IgA Elispot responses were also observed at 7 days after the first dose of the lowest dosage (5 μg) for both VLP antigens (Table 2). Notably, the antibody secreting cell (ASC) responses were biased to IgA vs. IgG and ASCs exhibited a mucosal homing (alpha 4/beta7) and chemokine (CCR10) receptor phenotype as assessed by flow cytometry (FIGS. 11A-11B; Table 3). As shown in Table 3, a greater number of ASCs exhibit mucosal homing markers (beta 7+, CD62L−) as compared to dual mucosal/peripheral homing markers (beta 7+, CD62L+). Table 4 shows the percentage of memory B cells per 10⁶ peripheral blood monocytes that respond to the VLP antigens. A larger percentage of antigen-specific memory B cells also express mucosal homing markers as compared to the dual mucosal/peripheral or peripheral homing markers. Similar responses were also observed in recipients who received the 15 μg and 50 μg doses (Tables 2-4).

TABLE 2 Day 7, Characterization of PBMC response. Approximation of Antibody Secreting Cells (ASCs)/million CD19+ cells. Vaccine Specific Percent Vaccine of ASC/million Response Total Norovirus- CD19+ cells—Day 7 Percent Circu- specific B IgA IgG IgA IgG Specific Specific lating cells GI.1 GI.1 GII.4 GII.4 to GI.1 to GII.4 PBMC Geometric 30947 13807 10947 3945 4.48% 1.49% 5.96% mean A1 5 μg dose (n = 5) Standard 6674 9780 3651 2261 Deviation A1 5 μg dose Geometric 25296 17004 7108 4336 4.23% 1.14% 5.37% mean A2 15 μg dose (n = 4) Standard 10846 18770 6055 5697 Deviation A2 15 μg dose Geometric 36158 20572 14103 2549 5.67% 1.67% 7.34% mean A3 50 μg dose (n = 4) Standard 11470 418 7627 2230 Deviation A3 50 μg dose Geometric 34183 9566 26213 11310 4.37% 3.75% 8.13% mean A4 150 μg dose (n = 4) Standard 32938 4466 89769 15226 Deviation A4 150 μg dose Placebo 0 152 0 108 0.02% 0.01% 0.03% (n = 2)

TABLE 3 ASC markers in vaccine and placebo recipients by flow cytometry—Day 7 Vac- cine Spe- cific Vaccine Per- Specific cent Percent Total per of % of % of % of Total million Total* Total % Total % Total ASC cells* Circu- CD19+ CD27+, CD27+, CD27+, CD27+, lating B cells CD38+, CD38+, CD38+, CD38+, PBMC that are CCR10+ CCR10+ CCR10+, CCR10+, Mu- CD27+ _Beta Beta Beta 7+ Beta 7+ cosal & 7+, 7+, CD62L(+) CD62L(+) Hom- CD38+ CD62L− CD62L+ &(−) &(−) ing Geo- 25.10% 6.86% 1.06%  2.78% 1656 0.17%  metric mean A1 5 μg dose (n = 5) Stand- 10.45 3.13 1.01 ard Devi- ation A1 5 μg dose Geo- 12.99% 16.98% 2.43%  4.63% 1355 0.14%  metric mean A2 15 μg dose (n = 4) Stand- 9.13 1.56 0.23 ard Devi- ation A2 15 μg dose Geo- 31.71% 26.43% 3.63% 12.01% 23915 2.39%  metric mean A3 50 μg dose (n = 4) Stand- 6.32 1.82 1.38 ard Devi- ation A3 50 μg dose Geo- 33.46% 30.06% 5.68% 15.74% 31350 3.14%  metric mean A4 150 μg dose (n = 4) Stand- 9.86 2.97 1.70 ard Devi- ation A4 150 μg dose Place-  1.26% 22.00% 0.87%  1.20% 5 0.001% bo (n = 2) *Assumes the majority of ASCs are norovirus-specific.

TABLE 4 Memory B cell responses in vaccine and placebo recipients—Day 7 Vac- cine Spe- Vaccine cific Specific Per- Percent Total per cent % % Total million of % of of % of % Memory cells* Total* Total Total Total CD27+, CD27+, Circu- CD19+ CD27+, CD27+, CD38+, CD38+, lating B cells CD38+, CD38+, CD138+, CD138+, PBMC that are CD138+, CD138+, CCR10+, CCR10+, Mu- CD27+, CCR10+ CCR10+ Beta 7+ Beta 7+ cosal CD38+, Beta 7+, Beta 7+, CD62L(+) CD62L(+) Hom- CD138+ CD62L− CD62L+ &(−) &(−) ing Geo- N/D N/D N/D N/D N/D N/D metric mean A1 5 μg dose Geo- 1.54% 11.58% 1.92% 0.21% 61 0.01% metric mean A2 15 μg dose (n = 4) Stand- 1.54 3.94 0.94 ard Devi- ation A2 15 μg dose Geo- 3.31% 16.10% 4.60% 0.68% 1364 0.14% metric mean A3 50 μg dose (n = 4) Stand- 1.11 2.16 0.97 ard Devi- ation A3 50 μg dose Geo- 1.56% 16.90% 8.10% 0.39% 778 0.08% metric mean A4 150 μg dose (n = 4) Stand- 0.22 3.26 4.57 ard Devi- ation A4 150 μg dose Place- 0.10% 12.50% 0.00% 0.01% 0 0%   bo (n = 1) *Assumes the majority of ASCs are norovirus-specific.

In the absence of an available direct viral neutralization assay due to the inability to culture Norovirus in vitro, functional assays which serve as substitutes for viral neutralization assays were conducted to measure functional antibodies in vaccines.

Using the carbohydrate H antigen blocking activity assay described above, the inhibition of GI.1 VLP binding to H antigen mediated by vaccine-induced serum antibodies was measured. Data are presented as geometric mean fold rise (GMFR) and seroresponse (4-fold rise) in Table 5, and as geometric mean titer (GMT) in Table 6. Surprisingly, after just one intramuscular injection of the vaccine formulation, significant carbohydrate blocking activity was observed in all dose groups; in fact, the administration of a second dose of vaccine did not significantly increase blocking activity compared to post-dose 1 levels. The inhibition of binding activity was maintained throughout the testing period, up to 56 days post dose 1.

TABLE 5 Carbohydrate Blocking Activity (HBGA BT50), Anti-Norovirus GI.1 Geometric Mean Fold Rise (GMFR) and Seroresponse (4-Fold Rise) Study Day 7 Days Post 28 Days Post 28 Days Dose 2 Dose 2 7 Days 21 Days Post Dose 1 (35 Days (56 Days Post Dose 1 Post Dose 1 (Pre-Dose 2) Post Dose 1) Post Dose 1) 4- 4- 4- 4- 4- Fold Fold Fold Fold Fold Treat- GMFR Rise GMFR Rise GMFR Rise GMFR Rise GMFR Rise ment (95% (95% (95% (95% (95% (95% (95% (95% (95% (95% Group N CI) CI) N CI) CI) N CI) CI) N CI) CI) N CI) CI) 5/5 mcg 9 26.6 88.9 9 25.1 88.9 9 19.7 100.0 9 20 88.9 9 16.6 77.8 VLP (8.3, (51.8, (8.9, (51.8, (8.2, (66.4, (7.7, (51.8, (5.7 (40.0, Vaccine 85.1) 99.7) 70.3) 99.7) 47.1) 100.0) 51.7) 99.7) 48.1) 97.2) 15/15 mcg 8 33.2 100.0 8 25.5 100.0 8 18.5 100.0 7 22.2 100.0 7 8.4 57.1 VLP (13.6, (63.1, (10.5, (63.1, (8.4, (63.1, (8.8, (59.0, (2.4, (18.4, Vaccine 80.8) 100.0) 61.8) 100.0) 40.6) 100.0) 56) 100.0) 29.6) 90.1) 50/50 mcg 10 38.6 100.0 10 27.9 100.0 10 20.9 100.0 10 19 100.0 9 10.2 77.8 VLP (18.3, (69.2, (13.4, (69.2, (10, (69.2, (9.9, (69.2, (4.6, (40.0, Vaccine 81.6) 100.0) 58) 100.0) 43.5) 100.0) 36.4) 100.0) 22.8) 97.2) 150/150 7 30.6 100.0 8 19.4 100.0 8 16.3 100.0 8 18.8 100.0 8 23.8 100.0 mcg VLP (16.3, (59.0, (13.1, (63.1, (11.7, (63.1, (12.8, (63.1, (17, (63.1, Vaccine 57.6) 100.0) 28.5) 100.0) 22.6) 100.0) 27.5) 100.0) 33.3) 100.0) Placebo 8 0.9 0.0 8 0.8 0.0 8 0.8 0.0 8 0.8 0.0 8 0.6 0.0 (0.8, (0.0, (0.7, (0.0, (0.6, (0.0, (0.7, (0.0, (0.3, (0.0, 1 36.9) 1.1) 36.9) 1.1) 36.9) 1.1) 36.9) 1.2) 36.9) Results based on all subjects receiving both doses of study product. Two subjects' data points are excluded due to a possible mix-up of specimens; one of these data points is a baseline specimen resulting in the subject not having fold rise data available for any time point.

TABLE 6 Carbohydrate Blocking Activity (HBGA BT50), Anti-Norovirus GI.1 Geometric Mean Titer (GMT) Study Day 7 Days 28 Days 28 Days Post Post Post Dose 2 Dose 2 7 Days 21 Days Dose 1 (35 Days (56 Days Pre- Post Post (Pre- Post Post Dose 1 Dose 1 Dose 1 Dose 2) Dose 1) Dose 1) Treat- GMT GMT GMT GMT GMT GMT ment (95% (95% (95% (95% (95% (95% Group N CI) N CI) N CI) N CI) N CI) N CI) 5/5 mcg 9 28.9 9 768.5 9 723.7 9 568 9 577.1 9 478.3 VLP (12.7, (344.1, (398.1, (321.8, (351.2, (293.3, Vaccine 65.9) 1716) 1316) 1003) 948.3) 780.1) 15/15 mcg 8 24.9 8 826.1 8 634.3 8 459.8 7 610.3 7 230.9 VLP (12.7, (524.9, (285.9, (225.3, (354.6, (105.2, Vaccine 48.7) 1300) 1407) 938.6) 1050) 506.7) 50/50 mcg 10 17.3 10 669.2 10 483.7 10 362.4 10 328.9 9 184 VLP (9.9, (329.1, (258.7, (192.9, (191.9, (97.2, Vaccine 30.3) 1361) 904.2) 680.7) 563.8) 348.3) 150/150 8 15.5 7 435 8 300.7 8 252.7 8 291.5 8 369.7 mcg VLP (11.1, (262.5, (173.9, (146.7, (171.5, (233.8, Vaccine 21.8) 720.8) 520) 435.2) 495.4) 584.6) Placebo 8 29 9 24.6 9 22.5 9 22.2 8 24.6 8 18.3 (9.1, (9.8, (8.8, (8.9, (8.4, (10.1, 92.8) 62.1) 57.3) 55.5) 72.6) 33.3) Results based on all subjects receiving both doses of study product. Two subjects' data points are excluded due to a possible mix-up of specimens.

Similarly, carbohydrate blocking activity of serum antibodies against GII.4 VLPs was measured. A significant response was observed in all dosing groups as measured by GMFR and seroresponse (Table 7) as well as GMT (Table 8). Similar to the antibody-mediated blocking of GI.1 binding described above, robust blocking of GII.4 VLP carbohydrate binding activity was detected after just one dose, and a second dose did not appear to enhance the blocking activity.

TABLE 7 Carbohydrate Blocking Activity (HBGA BT50), Anti-Norovirus GII.4 Geometric Mean Fold Rise (GMFR) and Seroresponse (4-Fold Rise) Study Day 7 Days Post 28 Days Post Dose 2 Dose 2 28 Days (35 Days (56 Days 7 Days Post 21 Days Post Post Dose 1 Post Post Dose 1 Dose 1 (Pre-Dose 2) Dose 1) Dose 1) 4- 4- 4- 4- 4- Fold Fold Fold Fold Fold Treat- GMFR Rise GMFR Rise GMFR Rise GMFR Rise GMFR Rise ment (95% (95% (95% (95% (95% (95% (95% (95% (95% (95% Group N CI) CI) N CI) CI) N CI) CI) N CI) CI) N CI) CI) 5/5 mcg 9 5 33.3 9 5.9 55.6 9 4.7 44.4 9 4.7 44.4 9 5 55.6 VLP (1.6, (7.5, (1.7, (21.2, (1.4, (13.7, (1.6, (13.7, (1.6, (21.2, Vaccine 16.1) 70.1) 20.3) 86.3) 15.7) 78.8) 13.8) 78.8) 15.9) 86.3) 15/15 mcg 8 11 62.5 8 9.2 62.5 8 7.4 62.5 7 7 57.1 7 5.6 57.1 VLP (2.7, (24.5, (3, (24.5, (2.5, (24.5, (2.1, (18.4, (2.3, (18.4, Vaccine 45.3) 91.5) 27.9) 91.5) 21.8) 91.5) 23) 90.1) 14) 90.1) 50/50 mcg 10 18.6 70.0 10 12.2 70.0 10 8.4 70.0 10 8.7 70.0 9 5.2 66.7 VLP (4.9, (34.8, (3.8, (34.8, (2.9, (34.8, (2.9, (34.8, (2.2, (29.9, Vaccine 70.8) 93.3) 39.4) 93.3) 24.1) 93.3) 26.1) 93.3) 12) 92.5) 150/150 7 10.1 57.1 8 5.5 50.0 8 4.4 50.0 8 4.3 37.5 8 3.1 25.0 mcg VLP (2, (18.4, (1.9, (15.7, (1.6, (15.7, (1.7, (8.5, (1.3, (3.2, Vaccine 51.8) 90.1) 16.5) 84.3) 12.2) 84.3) 10.7) 75.5) 7.2) 65.1) Placebo 8 1 0.0 8 1.1 0.0 8 1.3 12.5 8 1.8 12.5 8 2 12.5 (0.9, (0.0, (1, (0.0, (0.9, (0.3, (0.5, (0.3, (0.7, (0.3, 1.1) 36.9) 1.3) 36.9) 2.1) 52.7) 6.7) 52.7) 6.1) 52.7) Results based on all subjects receiving both doses of study product. Two subjects' data points are excluded due to a possible mix-up of specimens; one of these data points is a baseline specimen resulting in the subject not having fold rise data available for any time point.

TABLE 8 Carbohydrate Blocking Activity (HBGA BT50), Anti-Norovirus GII.4 Geometric Mean Titer (GMT) Study Day 7 Days 28 Days 7 Days 21 Days 28 Days Post Post Dose 2 Post Dose 2 Pre- Post Post Dose 1 (35 Days Post (56 Days Post Dose 1 Dose 1 Dose 1 (Pre-Dose 2) Dose 1) Dose 1) Treat- GMT GMT GMT GMT GMT GMT ment (95% (95% (95% (95% (95% (95% Group N CI) N CI) N CI) N CI) N CI) N CI) 5/5 mcg 9 40.3 9 202.1 9 236.9 9 189.7 9 188.7 9 201.6 VLP (18, (106.3, (133.4, (108.6, (118.7, (116.4, Vaccine 90) 384.3) 420.6) 331.3) 300.1) 349.5) 15/15 mcg 8 23.7 8 260.1 8 218.1 8 175.4 7 182.3 7 146.3 VLP (12.8, (95.1, (104.2, (82.7, (89.1, (92.4, Vaccine 43.8) 711.1) 456.3) 372) 372.8) 231.5) 50/50 mcg 10 28.4 10 527.2 10 345.2 10 238.3 10 246.5 9 160.2 VLP (13.1, (271.1, (195.5, (139.4, (138.7, (107.4, Vaccine 61.5) 1025) 609.6) 407.3) 438.2) 238.8) 150/150 8 63 7 721.8 8 347.7 8 277 8 267.9 8 193.5 mcg VLP (24.8, (344.6, (186.1, (145.6, (158.7, (121.6, Vaccine 160.4) 1512) 649.5) 527) 452.2) 308.2) Placebo 8 24.1 9 22.8 9 24.9 9 29.1 8 44 8 48.2 (12.9, (12.6, (12.7, (15.1, (12.6, (16.7, 45) 41.6) 48.7) 56.1) 154.2) 139.5) Results based on all subjects receiving both doses of study product. Two subjects' data points are excluded due to a possible mix-up of specimens.

Hemagglutination Inhibition assays (HAI) were also utilized to test the response of serum antibodies from vaccinated subjects against target Norovirus VLP antigens. Similar to carbohydrate H antigen binding studies, just one dose of VLP vaccine induced antibodies that inhibited hemagglutination in all dosing groups, as measured by GMFR (Table 9), 4-fold rise (Table 9), and GMT (Table 10). Though the level of inhibition of hemagglutination was maintained through the last day tested (28 days post dose 2, 56 days post dose 1), the second dose of VLP vaccine did not appear to enhance vaccine-induced antibody-mediated inhibition of hemagglutination.

TABLE 9 Hemagglutination Inhibition Assay Anti-Norovirus GI.1 Geometric Mean Fold Rise (GMFR) and Seroresponse (4-Fold Rise) Study Day 7 Days 28 Days 28 Days Post Dose 2 Post Dose 2 7 Days 21 Days Post Dose 1 (35 Days (56 Days Post Dose 1 Post Dose 1 (Pre-Dose 2) Post Dose 1) Post Dose 1) 4- 4- 4- 4- 4- Fold Fold Fold Fold Fold Treat- GMFR Rise GMFR Rise GMFR Rise GMFR Rise GMFR Rise ment (95% (95% (95% (95% (95% (95% (95% (95% (95% (95% Group N CI) CI) N CI CI) N CI) CI N CI) CI) N CI) CI 5/5 mcg 9 5.4 77.8 9 7 88.9 9 6.1 88.9 9 6 77.8 9 6.3 88.9 VLP (3, (40.0, (4.6, (51.8, (4.1, (51.8, (3.7, (40.0, (3.9, (51.8, Vaccine 9.8) 97.2) 10.7) 99.7) 9.3) 99.7) 9.5) 97.2) 10.3) 99.7) 15/15 mcg 8 8.9 100.0 8 9.5 87.5 8 7.1 75.0 7 8.5 85.7 7 8.1 100.0 VLP (4.4, (63.1, (4, (47.3, (3.1, (34.9, (4.1, (42.1, (4.4, (59.0, Vaccine 18) 100.0) 22.5) 99.7) 16.1) 96.8) 17.7) 99.6) 15.2) 100.0) 50/50 mcg 10 22.4 100.0 10 16.7 100.0 10 13.9 100.0 10 14.5 100.0 9 11.8 100.0 VLP (11.6, (69.2, (9.3, (69.2, (8.1, (69.2, (9.3, (69.2, (6.3 (66.4, Vaccine 43) 100.0) 29.8) 100.0) 24) 100.0) 22.7) 100.0) 21.9) 100.0) 150/150 7 12.6 85.7 8 11.1 100.0 8 8.4 100.0 8 8.4 100.0 8 7.3 100.0 mcg VLP (5.7, (42.1, (6.4, (63.1, (5, (63.1, (5, (63.1, (4.5, (63.1, Vaccine 28) 99.6) 19.3) 100.0) 14) 100.0) 14) 100.0) 11.9) 100.0) Placebo 8 1 0.0 8 1 0.0 8 1 0.0 8 0.9 0.0 8 1 0.0 (0.8, (0.0, (0.9, (0.0, (0.9, (0.0, (0.7, (0.0, (0.8, (0.0, 1.2) 36.9) 1.2) 36.9) 1.1) 36.9) 1.1) 36.9) 1.2) 36.9) Results based on all subjects receiving both doses of study product. Two subjects' data points are excluded due to a possible mix-up of specimens; one of these data points is a baseline specimen resulting in the subject not having fold rise data available for any time point.

TABLE 10 Hemagglutination Inhibition Assay Anti-Norovirus GI.1 Geometric Mean Titer (GMT) Study Day 7 Days 28 Days Post Dose Post Dose 28 Days Post 2 (35 2 (56 7 Days Post 21 Days Post Dose 1 (Pre- Days Post Days Pre-Dose 1 Dose 1 Dose 1 Dose 2) Dose 1) Post Dose 1) Treat- GMT GMT GMT GMT GMT GMT ment (95% (95% (95% (95% (95% (95% Group N CI N CI) N CI) N CI) N CI) N CI) 5/5 mcg 9 26.4 9 143.5 9 185.3 9 162.1 9 157 9 167.4 VLP (14.1, (53.6, (88.6, (83.3, (80.3, (88.4, Vaccine 49.4) 383.8) 387.6) 315.6) 307.1) 316.8) 15/15 mcg 8 11.9 8 105.3 8 113.1 8 84.2 7 103.3 7 99.2 VLP (6.1, (56.1, (42.5, (31.1, (43.3, (46.9, Vaccine 23.4) 197.6) 301.3) 227.6) 246.6) 209.7) 50/50 mcg 10 7.2 10 160 10 119.2 10 99.7 10 103.8 9 81.1 VLP (5.3, (79.4, (60.4, (51.8, (58.4, (38.8, Vaccine 9.6) 322.6) 235.1) 191.8) 184.5) 169.5) 150/150 8 9.2 7 114.1 8 101.6 8 77.2 8 77.2 8 67.3 mcg VLP (7.5, (50.9, (62, (51.8, (51.8, (44.7, Vaccine 11.3) 255.7) 166.4) 115) 115) 101.3) Placebo 8 16.8 9 16.6 9 16.1 9 16.6 8 15.4 8 16.2 (10.1, (11.7, (10.7, (11, (10, (10.8, 28.1) 1 23.7) 24.1) 25) 23.7) 24.4) Results based on all subjects receiving both doses of study product. Two subjects' data points are excluded due to a possible mix-up of specimens.

Inhibition of hemagglutination was also achieved when the target VLP was a mismatched virus. Vaccine-induced serum antibodies inhibited hemagglutination by a Houston virus strain VLP, as measured by GMFR and seroresponse (Table 11) as well as GMT (Table 12). In this case, the higher VLP vaccine doses afforded stronger responses, particularly as measured by 4-fold rise or GMT. GMFR and 4-fold rise were also significantly increased when the target VLP was the 2003 Cincinnati virus strain, as measured just 7 days post dose 1 (Table 13).

TABLE 11 Hemagglutination Inhibition Assay (Houston Virus Strain VLP), Anti-Norovirus GII.4 Geometric Mean Fold Rise (GMFR) and Seroresponse (4-Fold Rise) Study Day 7 Days 28 Days 28 Days Post Dose 2 Post Dose 2 7 Days 21 Days Post Post Dose 1 (35 Days (56 Days Post Dose 1 Dose 1 (Pre-Dose 2) Post Dose 1) Post Dose 1) 4- 4- 4- 4- 4- Fold Fold Fold Fold Fold Treat- GMFR Rise GMFR Rise GMFR Rise GMFR Rise GMFR Rise ment (95% (95% (95% (95% (95% (95% (95% (95% (95% (95% Group N CI) CI) N CI CI N CI) CI N CI CD N CI CI) 5/5 mcg 9 1.2 0.0 9 1.3 0.0 9 1.3 0.0 9 1.3 0.0 9 1.3 0.0 Vaccine (1, (0.0, (0.9, (0.0, (0.9, (0.0, (1, (0.0, (1, (0.0, VLP 1.5) 33.6) 1.7) 33.6) 1.7) 33.6) 1.7) 33.6) 1.6) 33.6) 15/15 8 1.7 12.5 8 1.6 12.5 8 1.5 0.0 7 1.5 0.0 7 1.6 0.0 mcg VLP (0.9, (0.3, (1.1, (0.3, (1.1, (0.0, (1, (0.0, (1.1, (0.0, Vaccine 3) 52.7) 2.4 52.7) 2.2) 36.9) 2.2) 41.0) 2.4) 41.0) 50/50 10 2 10.0 10 1.6 10.0 10 1.7 10.0 10 1.5 10.0 9 1.3 11.1 mcg VLP (0.9, (0.3, (0.8, (0.3, (0.9, (0.3, (0.9, 0.3, (0.8, (0.3, Vaccine 4.3) 44.5) 3.1) 44.5) 3.1) 44.5) 2.4) 44.5) 2) 48.2) 150/150 7 4.3 57.1 8 2.6 50.0 8 1.9 12.5 8 1.9 12.5 8 1.7 12.5 mcg VLP (1.5, (18.4, (1.2, (15.7, (1.1, (0.3, (1.1, (0.3, (1.1, (0.3 Vaccine 12.4) 90.1) 5.8) 84.3) 3.3) 52.7) 3.5) 52.7) 2.6) 52.7) Placebo 8 1 0.0 8 1.1 0.0 8 1.1 0.0 8 1.2 12.5 8 1.1 12.5 (0.9, (0.0, (0.9, (0.0, (1, (0.0, (0.8, (0.3, (0.7, (0.3 1.1) 36.9) 1.3) 36.9) 1.2) 36.9) 1.9) 52.7) 1.8) 52.7) Results based on all subjects receiving both doses of study product. Two subjects' data points are excluded due to a possible mix-up of specimens; one of these data points is a baseline specimen resulting in the subject not having fold rise data available for any time point.

TABLE 12 Hemagglutination Inhibition Assay (Houston Virus Strain VLP), Anti-Norovirus GII.4 Geometric Mean Titer (GMT) Study Day 7 Days 28 Days 28 Days Post Post Post Dose 2 Dose 2 7 Days 21 Days Dose 1 (35 Days (56 Days Pre- Post Post (Pre- Post Post Dose 1 Dose 1 Dose 1 Dose 2) Dose 1) Dose 1) Treat- GMT GMT GMT GMT GMT GMT ment (95% (95% (95% (95% (95% N (95% Group N CI) N CI) N CI) N CI) N CI) CI) 5/5 mcg 9 143.5 9 177.4 9 180.8 9 180.8 9 189.1 9 180.8 VLP (97.9, (122.7, (114.4, (114.4, (119.2, (122.7, Vaccine 210.3) 256.5) 285.6) 285.6) 299.9) 266.3) 15/15 mcg 8 129.8 8 218.3 8 207.5 8 200.2 7 169.5 7 187.2 VLP (86.4, (129.2, (134.8, (132.8, (114.1, (119.1, Vaccine 194.9) 368.8) 319.3) 301.7) 252) 294.2) 50/50 mcg 10 161.9 10 323.8 10 252.5 10 273.9 10 242.5 9 195.2 VLP (119.7, (156.5, (130.4, (150.9, (150.2, (125, Vaccine 219) 669.8) 489.2) 497.2) 391.5) 304.9) 150/150 8 210.6 7 853.5 8 546.2 8 406.3 8 406.3 8 354.1 mcg VLP (108.8, (297.4, (237.6, (201.5, (180.3, (184.6, Vaccine 407.5) 2449) 1255) 819.1) 915.4) 679.5) Placebo 8 148.9 9 150.1 9 157 9 167.4 8 183.6 8 162.4 (73.8, (80.1, (77.9, (91.4, (95, (88.5, 300.3) 281.1) 316.5) 306.4) 354.5) 297.9) Results based on all subjects receiving both doses of study product. Two subjects' data points are excluded due to a possible mix-up of specimens.

TABLE 13 Inhibition of Hemagglutination in placebo versus 50/50 μg VLP vaccine Hemagglutination Inhibition Assay (2003 Cincinnati Virus Strain VLP), Anti-Norovirus GII.4 Geometric Mean Fold Rise (GMFR) and Geometric Seroresponse (4-Fold Rise) Results by Treatment Group 7 Days Post Dose 1 Treatment Group N GMFR (95% CI) 4-Fold Rise (95% CI) Placebo  2 1.0 (0.6, 1.8)  0.0 (0.0, 84.2) 50/50 μg VLP Vaccine 10 4.4 (1.6, 11.9) 50.0 (18.7, 81.3)

The results from this study demonstrated that the Bivalent IM Norovirus VLP vaccine was generally well tolerated. The immunogenicity data suggested that a single vaccine dose may be sufficient to protect seropositive human adults. The results from the carbohydrate blocking activity and hemagglutination inhibition assays provided further evidence that a single vaccine dose induced serum antibodies with potent anti-Norovirus activity. The magnitude and rapidity of the observed immune responses following a single parenteral dose in humans were dramatic when compared to earlier immune responses reported by multiple nasal VLP vaccine administrations at much higher VLP dosages (El Kamary et al. (2010) J Infect Dis, Vol. 202(11): 1649-1658). These responses were also superior to those induced by orally administered Norovirus VLPs (Tacket et al. (2003) Clin Immunol 108:241-247; Ball et al. (1999, Gastroenterology 117:40-48) as well as those induced by Norovirus VLPs produced by transgenic plants (Tacket et al. (2000) J Infect Dis 182:302-305). In particular, this intramuscular vaccine formulation produced anamnestic responses within seven days of immunization and maximal serum antibody responses were observed after a single dose, including a significant IgA response and functional carbohydrate blocking activity and hemagglutination inhibition activity. Thus, this Norovirus bivalent vaccine induced a strong, protective immune response in humans that was superior to immune responses induced by any currently available Norovirus vaccine.

Example 2. Dose Escalation, Safety and Immunogenicity Study of Intramuscular Norovirus Bivalent Virus-Like-Particle (VLP) Vaccine in Humans (LV03-104 Study)

The following example provides the remaining planned portion of the clinical study described in Example 1, wherein a randomized, multi-site, dose-escalation study is conducted in adults ≥18 years of age of the safety and immunogenicity of four dosage levels of an intramuscular (IM) Norovirus Bivalent VLP Vaccine adjuvanted with monophosphoryl lipid A (MPL) and aluminum hydroxide (AlOH), compared to placebo. Subjects will receive two doses of the vaccine or placebo, by intramuscular (IM) injection, 28 days apart using a 1.5 inch (38 mm) needle. This example is intended to further illustrate the principles of the present invention.

Cohort A has completed enrollment in the study and was described above in Example 1. Cohort B contains ˜20 subjects 50-64 years of age. Cohort C contains ˜30 subjects 65-85 years of age. Approximately 98 subjects are enrolled in the study as a whole.

In Cohort B, −20 subjects 50-64 years of age are enrolled and randomized 1:1 to receive vaccine (N=10) or placebo (N=10). After the 7-day post Dose 2 safety data (Study Day 35) are available for review from subjects in Cohort B, subjects in Cohort C are eligible to receive their initial dose. In Cohort C, −30 subjects 65 to 85 years of age are enrolled and randomized 1:1:1 to receive vaccine adjuvanted with MPL and AlOH (N=10), or vaccine adjuvanted with AlOH alone, i.e. no MPL (N=10), or placebo (N=10). The antigen concentrations of the norovirus VLPs and of the AlOH in the two vaccine formulations to be evaluated in Cohort C are identical; only the presence or absence of MPL is different.

The Norovirus Bivalent VLP Vaccine contains genogroup I, genotype 1 (GI.1) and genogroup II, genotype IV (GII.4) VLPs as the antigens, and Monophosphoryl Lipid A (MPL) and aluminum hydroxide (AlOH) as adjuvants, sodium chloride (NaCl) and L-histidine (L-His) as buffer (pH 6.3-6.7), ethanol and water for injection. The GII.4 VLPs comprised a capsid sequence of SEQ ID NO: 1, which was derived from three GII.4 strains.

The single dosage of vaccine selected for further evaluation in Cohorts B and C is the lowest dosage in Cohort A that results in the most robust and reproducible immune response that is also generally well tolerated. The Day 56 safety and immunogenicity data from subjects in Cohort A is reviewed by the CSM/SMC and the bivalent dosage is selected for evaluation in Cohorts B and C.

The subjects keep a daily memory aid of solicited symptoms including four local injection site reactions, such as pain, tenderness, redness, and swelling, and 10 systemic signs or symptoms including daily oral temperature, headache, fatigue, muscle aches, chills, joint aches and gastrointestinal symptoms of nausea, vomiting, diarrhea, abdominal cramps/pain for Days 0 through 7 after each dose of IM Norovirus Bivalent VLP Vaccine or control. The redness and swelling at the injection site are measured and recorded daily for 7 days after each injection.

Interim medical histories are obtained at each follow-up visit on Days 7+3, 21+3, 28+3, 35+3, 56+7, 180+14, and 393+14 and at the follow-up telephone call on Day 265+14; subjects are queried about interim illness, doctor's visits, any serious adverse events (SAEs), and onset of any significant new medical conditions. Subjects have a CBC with WBC differential and platelet count, and serum BUN, creatinine, glucose, AST, and ALT assessed at screening and on Days 21 and 35 (˜7 days after each dose) to assess continuing eligibility and safety, respectively.

Blood from subjects is collected before vaccination on Day 0 and on Days 7+3, 21+3, 28+3, 35+3, 56+7, 180+14, and 393+14 to measure serum antibodies (IgG, IgA, and IgM separately and combined) to IM Norovirus Bivalent VLP Vaccine by enzyme-linked immunosorbent assays (ELISA). Serum carbohydrate blocking activity and serum HAI antibodies are also measured.

The methods described above for Cohort A are used to analyze the blood samples collected from immunized individuals or individuals receiving the placebo. The results of the study will be employed in the development of a clinical protocol for administration of the vaccine formulations of the invention.

The present invention is not to be limited in scope by the specific embodiments described which are intended as single illustrations of individual aspects of the invention, and functionally equivalent methods and components are within the scope of the invention. Indeed, various modifications of the invention, in addition to those shown and described herein, will become apparent to those skilled in the art from the foregoing description and accompanying drawings using no more than routine experimentation. Such modifications and equivalents are intended to fall within the scope of the appended claims.

All publications, patents and patent applications mentioned in this specification are herein incorporated by reference into the specification to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference.

Citation or discussion of a reference herein shall not be construed as an admission that such is prior art to the present invention. 

1. A buffered composition comprising a first monovalent VLP derived from a first Norovirus genogroup and a second monovalent VLP derived from a second Norovirus genogroup wherein said buffer is L-histidine, and wherein the composition is formulated as a liquid.
 2. The buffered composition of claim 1, wherein said L-histidine is present at a concentration of between about 15 mM to about 50 mM.
 3. The buffered composition of claim 2, wherein said L-histidine is present at a concentration of between about 20 mM to about 25 mM.
 4. The buffered composition of claim 1, wherein the pH of the composition is between about 6.0 to about 7.0.
 5. The buffered composition of claim 4, wherein the pH of the composition is between about 6.2 to about 6.8.
 6. The buffered composition of claim 1, further comprising a pharmaceutically acceptable salt.
 7. The buffered composition of claim 6, wherein the salt is selected from the group consisting of sodium chloride, potassium chloride, sodium sulfate, ammonium sulfate and sodium citrate.
 8. The buffered composition of claim 7, wherein said salt is sodium chloride.
 9. The buffered composition of claim 8, wherein the concentration of sodium chloride is between about 10 mM and about 200 mM.
 10. The buffered composition of claim 9, wherein the concentration of sodium chloride is between about 100 mM and about 150 mM.
 11. The buffered composition of claim 1, wherein said first Norovirus genogroup is genogroup I.
 12. The buffered composition of claim 1, wherein one of the Norovirus genogroups is genogroup II.
 13. The buffered composition of claim 11, wherein the second Norovirus genogroup is genogroup II.
 14. The buffered composition of claim 13, wherein the first monovalent VLP is derived from Norovirus genotype GI.1 and the second monovalent VLP is derived from Norovirus genotype GII.4.
 15. The buffered composition of claim 13, wherein said second monovalent VLP contains capsid proteins derived from a consensus sequence of genogroup II noroviruses.
 16. The buffered composition of claim 1, further comprising at least one adjuvant.
 17. The buffered composition of claim 16, wherein said adjuvant is selected from the group consisting of monophosphoryl lipid A (MPL) and alum.
 18. The buffered composition of claim 1, further comprising MPL and alum.
 19. A method of inducing an immune response in a subject, comprising administering to the subject the buffered composition of claim
 1. 20. A vaccine formulation comprising the composition of claim
 1. 21. A method of inducing an immune response in a subject, comprising administering to the subject the vaccine formulation of claim
 20. 